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Published July 12, 2021

A sudden inrush of water, a panicked scramble to shut watertight doors, and more than a hundred men were trapped in a submarine beneath the water. It’s hard to imagine a more terrifying and claustrophobic situation.

But the vessel had an escort above the waves, they were relatively close to shore, and close to the surface, too – or at least, one end of it was – so rescue wouldn’t be too difficult, surely?

The idea of the submarine dates back as far as 1578, but it was only with the invention of torpedoes and electric power that they became vital weapons of war.

World War One proved their military abilities, with perhaps the most infamous moment coming when the German U-Boat U-20 sank the passenger liner Lusitania in May 1915. So, in the 1930s, it seemed obvious that submarines would play a large part in the next war.

Accordingly, the British Admiralty drew up designs for a new class of submarine; the T-Class, with every vessel of this type bearing a name which began with the letter T. 

One of these was the HMS Thetis; the contract to build her was awarded to Cammell Laird, in Birkenhead, with work beginning on the 21st of December 1936. Her name was taken from Greek mythology – Thetis was the mother of Achilles.

She was ceremoniously christened with a bottle of champagne on the 29th of June, 1938; then began the fitting out process. Some of the crew were assigned at this point – Lieutenant Commander Guy Bolus, who was to be the Captain, two officers and four ratings “stood by” from just before launch, and a further 12 senior ratings joined partway through the fitting out. At the end of February, 1939, the rest of the crew’s complement joined. 

The first trials of the Thetis were scheduled for March. These would be conducted in Cammell Laird’s wet basin, a safe, enclosed environment for testing the sub’s underwater capabilities. Machinery trials were held in Liverpool Bay in mid-April, then at the end of the month she went up to Scotland, where she was due to carry out engine, steering and diving trials in the naturally protected waters of Gare Loch on the River Clyde.

Unfortunately, the trip up to Scotland revealed a number of issues which meant that the trials could not be completed. 

So it was that the last trials came to be rescheduled and relocated to Liverpool Bay, on the 1st of June, 1939.

In addition to the crew of the Thetis, there were other naval officers on board that day, including Captain H.P.K. Oram, commander of the Fifth Submarine Flotilla, which Thetis would join upon commissioning, and the commanders of the Taku and Trident, two other submarines being built at Cammell Laird. There were also overseeing officers from the Admiralty, twenty-six employees of Cammell Laird, a few men from Vickers Armstrong, who were building other T-class submarines, a steering gear fitter from a company called Brown Brothers, Mersey pilot Norman Wilcox, and two men from Liverpool City Caterers, there to serve lunch. In total, 103 men, almost twice the submarine’s usual complement. 

Thetis would be accompanied that day by a tug called Grebe Cock, captained by Alfred Ernest Godfrey. He took on board two Navy men, Lieutenant Richard E. Coltart and Leading Wireless Telegraphist V.J. Crosby, who would be responsible for communications, and two men from Cammell Laird. The Grebe Cock’s main duty would be to stand by and keep a look out while the Thetis was submerged, making sure no surface vessels strayed into the dive area while she was under. They were also told that they would be taking on board passengers who were getting off Thetis while the dives were taking place.

However, when they reached the dive area, Bolus called to them through a megaphone:

“We are about to dive. No one is leaving the Thetis. All are accompanying us on board for the dive. My diving course is 310°. I want you to follow on my port quarter, Captain, at a distance of half a mile.”

Similarly, although the Number One Pilot Boat had specific instructions that they were to pick up the Mersey Pilot, Norman Wilcox, he waved them away; he had apparently decided to stay on the submarine.

While most of the men on board had no choice about accompanying the dive – they were essential to the trials – there were a number like Wilcox who could, or should, have disembarked. Yet all chose to remain; presumably, they thought it an exciting opportunity, and not one to pass up.

So, the crew took their positions, while the others were either distributed throughout the vessel based on their specialities, or simply staying out of the way.

The Thetis was divided into six compartments, with watertight bulkheads and doors separating them. At the very front was the torpedo tube compartment, followed by the torpedo stowage compartment, then the accommodation section. Beneath the tower lay the control room, and behind it, the engine room and, finally, the steering compartment. 

At 1.40pm, Bolus sent a signal to Fort Blockhouse, also known as HMS Dolphin, the submarine service’s headquarters.

“From H.M.S. Thetis. Important. Diving in position 53″35′ North, 04000′ West, for three hours.”

He received an acknowledgement at 1.56, and gave orders to begin the dive.

The Thetis, however, stubbornly remained on the surface.

Aboard the submarine, the crew were trying to establish why they weren’t going down. First Lieutenant Chapman was seen going through the boat, checking on different valves connected with the dive, and the auxiliary ballast tanks were carefully filled, checking for leaks the whole time.

Because it seemed that the problem was with the front end in particular being too light, the question was raised about whether the torpedo tubes were flooded. 

The torpedo tube compartment held six torpedo tubes, stacked in pairs. Numbers five and six lay beneath the normal water level when the submarine was on the surface, and when they weren’t being used for shooting torpedoes they could be used as ballast tanks.

Captain Oram asked if five and six were full of water; somebody replied that he thought they were not. It has never been established who that was. 

First Lieutenant Chapman checked the trim statement. This was a piece of paper with a list of all the ballast tanks printed on it; before leaving Birkenhead it had been filled in to show how much each tank held. At the bottom – written in, as it wasn’t part of the list – it said that torpedo tubes Number Five and Six were full.

In addition, the Thetis’ log read: “10.55 flood 5 & 6 tubes. 10.56 5 & 6 tubes flooded.”

However, when Lieutenant Woods, the torpedo officer, asked Mr Robinson, one of the Cammell Laird’s staff on board, whether they should be flooded or not, he was told that they were not meant to be full.

Because of this confusion, Woods decided to physically check the torpedo tubes.

Each tube had a test cock on the rear door; this consisted of a small hole in the door itself, and a pipe-like lever on the outside, in the torpedo tube compartment. When the lever was swivelled into position, its hole lined up with the hole in the door. If there was water inside the torpedo tube, a small amount would squirt out. If it wasn’t flooded, there should be a puff of air. 

When Woods tested them, a dribble of water came out of number 6 tube, showing that it had some water in it, but was probably not completely full. Nothing came out of the Number 5 test cock. 

He then checked the mechanical indicators which showed whether the bow caps – the exterior doors between the torpedo tubes and the sea – were open or shut. He would later say;

“I remember repeating in my mind, as I looked at each indicator, the words “Shut”, “Shut”, “Shut”, looking at Number Five first and then progressing upwards. I was satisfied at the time that it did show me shut.”

However, those indicators weren’t exactly straightforward. There were six indicators, one for each tube, in connected pairs and set in a vertical line, but they weren’t arranged in numerical order. From top to bottom, they went Two, One, Four, Three, Six, Five. On top of that, the indicators were mirrored on each pair. On Two, Four, and Six, the indicator showed Shut if it was to the left, and Open if it was to the right. On One, Three, and Five, Open was on the left, and Shut was on the right. 

It was said at the time that the crew were highly trained and unlikely to mistake the readings on the indicators, but it must also be said that such counter-intuitive design could not have been helpful.

Woods then wanted to check each of the torpedo tubes in turn, to be sure they weren’t leaking. He started at the top, assisted by his colleague Leading Seaman Hambrook, using the test cock on each before opening the rear door. One, Two, Three and Four were all checked and found to be dry. He skipped number Six, because he already believed it was at least half full.

“I opened Number Five test cock in the same manner previously and there was no sign of air or water. Then assisted by the rating mentioned, I commenced to open Number Five rear door.”

They found the door to be very stiff; Hambrook had to kick the lever to get the door to move. As it began to open, a trickle of water came out. Neither man thought this was unusual, assuming it had not been drained properly after earlier trials.

But the trickle abruptly became a torrent as the door burst fully open.

On the surface, Crosby was watching the Thetis closely for his log. Her bows submerged, but her stern rose; she levelled off with her guardrails awash, then the stern rose again; she levelled off once more, awash up to her gun and half the bridge.

“She remained like that for a very short time, and then dropped down bodily with very much the same effect as you would get if you pushed a round stick into a deep pond straight down.”

The Grebe Cock’s captain was also watching. Although he had no experience with submarines, he didn’t think the Thetis was behaving as it should.

“…She seemed to level up a bit. She then went down by the head and appeared to me to be in trouble. I thought she was trying to make surface again. She then went down by the head again and this time disappeared completely. She appeared to me to go down like a stone.”

It was two minutes to three.

In the torpedo tube compartment, there was chaos, but not panic. The men knew that they had to evacuate the compartment and close the watertight door to prevent the flooding from extending throughout the entire submarine. As well as Woods and Hambrook, there were at least three to five other men in the immediate area; Woods shouted for everyone to leave the area. They all moved as quickly as they could, but Hambrook had been injured by the sudden rush of water, and Woods had to help him out.

There are two things that you want from a watertight door in such an emergency; that it be quick to close, and that it be easy. Unfortunately, in this case, it was neither.

Firstly, all the doors in the submarine closed towards the control room, in the centre. This was to ensure that, if a compartment was flooded, the water pressure would tend to hold the doors closed rather than force them open. However, with the front of the submarine rapidly flooding, it was quickly sinking into a steep angle – so the door now had to be pulled upwards to get it closed, and these were very heavy doors. 

Secondly, securing the door shut wasn’t done with the quick spin of a handwheel, or the drop of a lever; instead, it had no less than eighteen butterfly bolts around its edge. The Admiralty had originally specified a quick-locking door with a wheel, but the design had been changed to cut costs.

As the men tried to shut the door, they first found that a latch was holding it open, and someone had to jump back through into the flooding compartment to release it, and then they found that some of the door’s clips were hanging in the way, catching on the coaming – the raised lip around the door hatch – and stopping them from closing it completely. 

As the water continued to rise, it was clear that they were not going to be able to secure that door, and they retreated further, leaving the torpedo stowage compartment to secure the next door along.They had been able to secure just one of the clips.

The torpedo stowage compartment was where the civilian caterers had set up for lunch, so it was full of extra furniture and loose equipment that impeded their escape. Woods later said,

“I found great difficulty in climbing out of the compartment, due to the angle of the ship and the fact that tables, stools and boxes were falling from the aft end of the compartment on top of us. I slipped back several times, as my shoes were wet… Mitchell was ten seconds behind me.”

Meanwhile, other men were approaching the problem; Leading Stokers Arnold and Cunningham reached the watertight door between the accommodation area and the torpedo stowage compartment.

Arnold later said,

“I guessed what had happened and tried to shut the bulkhead door… People were still in the torpedo stowage and tube compartments at that time, they were trying to close the fore-end door, but the water was coming in so quickly they had to get into the accommodation space where I was…
Leading Stoker Cunningham, Engine Room Artificer Howell and myself tried to shut the door. We had several attempts, but as fast as we tried to shut it people were pulling it open to get through. We were going to shut them in, but they kept coming aft one by one to pull the door open and get through, so that we could not get the door shut. Eventually they all got through and we got the door watertight. These people all eventually got out. We had some difficulty in shutting the door owing to the steep angle of the boat.” 

It may seem that Arnold’s intention of shutting the men in was cruel, but this was a well known dilemma for submariners. Woods had considered the same thing before assisting Hambrook, saying later; 

“It occurred to me that what I ought to do was close the door on him, but I preferred to wait and assist him. I had to assist him out of the compartment, which meant that some time was wasted before the port watertight door could be closed.”

If shutting the door on one man, or a handful of men, meant saving the ship, and the rest of the crew, it was expected that the door would be shut. But it wasn’t. 

In the control room, the crew had been alerted to the problem by a sudden rush of air, pushed ahead of the water, and the abrupt dipping of the vessel, throwing many of the men around the compartment. Captain Oram told Bolus to blow the main ballast tanks immediately; this meant blowing compressed air into the top, forcing the water out through the bottom and increasing the vessel’s buoyancy. However, the main tanks could only vent about two tons of water per second, while the open torpedo tube was letting in around three and a half tons per second. Bolus stopped blowing the tanks, presumably to save the compressed air which might be needed later, and ordered all unnecessary lights be turned off to save battery power.

Over the next half an hour, the Thetis began to settle on the seabed; Bolus ordered indicator buoys to be released, to mark their position, and the crew began to try and work out what they could do to escape. 

Just as the Titanic was designed to be able to float with up to four of her watertight compartments flooded, the Thetis was similarly able to withstand flooding in one compartment – but with two now either completely flooded or rapidly filling, it was obvious that the ship couldn’t rise on its own unless they could get the water out. 

There was a connection on the ship’s high-pressure air system which would allow them to blow air into the torpedo compartment, in the same way it was blown into the ballast tanks, but the problem was that the compartment wasn’t designed for that. There was a hatch on the top of the compartment, used for loading torpedoes onto the ship, and it was not designed to take pressure from inside. If, while blowing air into the compartment, they put more pressure on the inside of the hatch than the sea was exerting on it from the outside, the air would go out through the hatch – and let even more water in.  

The other option was to pump the water out, but before they could do that the door to Number 5 Torpedo Tube would have to be closed. This meant that somebody had to go back into the flooded compartment.

It was possible to do this because of the location of the forward escape chamber; it was set into the bulkhead between the accommodation area and the torpedo stowage compartment, with entrances on both sides as well as the escape hatch at the top. That meant it could be used as an air lock, allowing access to the forward compartments without opening the rest of the submarine to flooding.

Woods later recalled;

“Lieutenant Chapman said he would make an effort to get through and close Number Five rear door. I told him two men were necessary for a job like this. He insisted on going alone.”

Chapman had limited equipment to help him. He wore his normal clothes, but added some heavy eyebolts as weights to stop him floating. There were rubber waterproof torches somewhere on the Thetis, but they couldn’t be located, so instead they wrapped an ordinary torch in electrical tape. Finally, to allow him to breathe, he would use a Davis Submarine Escape Apparatus, or DSEA.

Invented in 1910, and adopted by the Royal Navy in 1929, the DSEA was an oxygen rebreather. It had a rubber bag containing a cylinder of compressed air, for both breathing and buoyancy, connected by a tube to a mouthpiece. A soda lime filter removed carbon dioxide as the wearer breathed out, a nose clip ensured they breathed only through the tube, and a pair of goggles completed the set. Altogether, the set could provide oxygen for up to thirty minutes. While it was designed for submarine escape – allowing the user to breathe, and managing oxygen pressure to avoid lung injury as they ascended to the surface – it could also be used as a diving set in a pinch.

Chapman stepped inside the escape chamber, the door was secured behind him, and they started the “flooding up” process to fill it with water. It would take a few minutes to fill, but then the pressure would equalise and he would be able to open the door into the flooded torpedo stowage compartment, and make his way forward to complete his task.

That was the theory; in practice, before the escape chamber was completely full, Chapman started pounding on the door, signalling for them to stop. He was suffering severe pain in his chest and ears, and was unable to continue. They drained the escape chamber down, and a disappointed Chapman rejoined the rest of the crew.

Woods volunteered to make his own attempt, but he wanted someone to go with him, so he was joined by Petty Officer Mitchell. The idea was for Mitchell to remain by the escape chamber, while Woods, with a rope tied around his waist, went forward. The rope would allow him to communicate through tugs, and help him find his way back. Moreover, Woods said, “I felt that it would give me more confidence if I could maintain contact with someone.”

“We entered the compartment and it was flooded from outside. When the water had reached our eyes Petty Officer Mitchell was drumming on his ears to say he was in great pain. I allowed the flooding to go on for a few more seconds hoping that he would overcome it, but he still exhibited signs of great pain so I gave the signal for them to drain down.”

Although disappointed for a second time, the men did not give up. Woods volunteered to try again – after all, he had not experienced the same pain as the other men – this time accompanied by Acting Petty Officer Smithers.

“We carried out the same procedure as before, but Petty Officer Smithers showed signs of distress and after waiting for a few seconds I again gave the signal to drain down. Petty Officer Smithers afterwards said that he felt his heart was paining him.”

After the third attempt had been abandoned, two more men, both engine room stokers, wanted to make an attempt, but Bolus decided against it. 

The gravity of their situation was quickly becoming clear to all on board.

The standard complement of the Thetis was between 51 and 59 men – sources vary on the exact number. Under normal circumstances, the vessel was thought to have enough breathable air to last 48 hours. However, on this dive she was carrying roughly twice as many men, so the time they could wait for rescue was immediately halved. Add to that the fact that two compartments were flooded, so their air was gone, and time was even shorter. 

They did have the Davis escape apparatus, and the Admiralty had followed regulations which required enough for everyone on board, plus a third again, so they had provided 131 sets. However, 29 were stored in the torpedo stowage compartment, and were now out of reach. Another nine had been taken out for overhauling, and left ashore. That meant that they were ten short.

And leaving the submarine using the escape chamber and DSEA was not a guarantee of survival. If there wasn’t a ship above waiting to pull the escapees out of the water, they would be left floating helplessly, and most likely lose their life anyway.

Unfortunately, they had no direct contact with the Grebe Cock, and their ASDIC equipment – an early form of sonar – had been broken when they hit the sea bed. Had it been functioning, they would have been able to detect nearby surface vessels, and even communicate with them if they were ASDIC equipped. The Grebe Cock was not, but the crew expected that an ASDIC equipped ship would quickly be despatched to their location once they failed to resurface.

Meanwhile, on the Grebe Cock, Lieutenant Coltart initially saw no reason for concern, as the sub hadn’t released any smoke signals or indicator lights to show distress. 

They waited.

The diving trial schedule said that they would submerge and obtain trim, test battery ventilation and look through the ship for leaks, then surface, before making a second dive to periscope depth, so they shouldn’t have been down for long, but time continued to pass without any sign of her.

By 4.45pm, Coltart was concerned. However, the Grebe Cock had only limited radio capability; the only way they could contact anyone else involved in the trial was to send a message to Seaforth Radio – with whom they had only a patchy connection – and ask them to forward it to the relevant parties. 

Coltart sent a signal in this way to Fort Blockhouse, intended to convey his concern without raising panic. It read:

“To Captain S5, Fort Blockhouse, Gosport. Hampshire. From tug attending on Thetis. What was duration of Thetis dive? Coltart”

It took nearly ten minutes for Seaforth to receive and acknowledge that message – and it would take a lot longer for it to get to its final destination. It was sent on by telegram to Gosport Post Office, and since it wasn’t marked urgent or important, was then handed on to a delivery boy on a bicycle, who set off for Fort Blockhouse, but got a puncture on the way. It was some time around quarter past six – an hour and a half after it had been sent, and more than three hours after the Thetis had dived – when it finally reached Duty Staff Officer Commander Fawkes.

By this time, headquarters were already concerned about the Thetis; they had expected her surface signal at around 4.40pm. Some delay was not unusual, especially with a submarine’s first dive. Their wireless might malfunction, or they might not be able to send a signal out if the radio mast was too wet. The Wireless Office had been told to call out to Thetis every ten minutes, and at 5.30 Fawkes was attempting to contact Rear Admiral Watson, the overall commander of Fort Blockhouse, who was unfortunately off sick, and Watson’s Chief of Staff.

At 5.50, he spoke to Plymouth Duty Officer Bayne. The two men would later recall this conversation in different lights; Fawkes stated that he told Bayne the details and added, “I am definitely not assuming that an accident has taken place yet, but naturally I am anxious.”

 Bayne, however, recalled being told “there was no cause for anxiety” and that they were “expecting a signal at any moment.”

Knowing that the HMS Brazen was in the vicinity, after gunnery trials off Belfast, he suggested that the ASDIC-equipped ship could easily be redirected. “There is no need to take action”, he [Fawkes] replied. I gained the impression that he was not keen on any action to be taken then, and he said to me, “If you make any signal, make it code”.’

He did signal the Brazen anyway, at around 6.20, but without noting any urgency.

Then, of course, Coltart’s message finally arrived. At this point, Fawkes decided that they must assume an accident had taken place, and act accordingly. He contacted Bayne again, and at 6.50 Bayne sent another signal to the Brazen, advising them to proceed at top speed to find the Thetis.

As well as the Brazen, the 6th Destroyer Flotilla was despatched from Portland, and the Air Ministry sent five planes down from Abbotsinch to conduct an air search.

The Royal Navy’s dedicated diving vessel, HMS Tedworth, was also ordered out; unfortunately at the time they were moored on the River Clyde with absolutely no coal on board, so they were delayed by the need to refuel before they could depart.

At this point, command of the situation fell to Commander-in-Chief Plymouth, Admiral Sir Martin Eric Dunbar-Nasmith VC, an experienced submarine commander. He was also personally acquainted with Liverpool’s Water Bailiff and Marine Surveyor, Commander Hubert Viner Hart; unsurprisingly, then, Hart got a call at around 8.30pm.

Hart recalled,

“The gist of the message was to this effect, that the C-in-C Plymouth [Nasmith] feared that an accident had happened to this submarine; that as he knew me personally, and he also knew that I possessed salvage vessels and facilities always available, would I immediately go out and render what assistance I could.”

He called for the Liverpool Port’s Wreck Master, Charles Brock, and other specialists to set out on the Mersey Harbour vessel, Vigilant. The request from Naismith was considered so urgent that the Vigilant would set out at 9.45 with only half her crew; the rest were to be ferried out afterwards. Hart also asked for the port’s camels – unpowered barges used for salvage – to be prepared, although they couldn’t be towed out until high tide.

It was nine pm when the first searchers – HMS Brazen and the planes – reached the area. Unfortunately, sunset was at 9.04, making it a difficult task.

The Grebe Cock had, with some difficulty, anchored in the meantime, connecting her two anchor chains together so that they would reach the bottom. They knew, by that point, that despite their efforts to maintain their location they were only roughly near the last known location of the Thetis, but that would at least be better than nothing.

Starting from the location of the Grebe Cock, and going westward because that was the Thetis’ heading, the Brazen started searching on a grid pattern, using the ASDIC equipment to search an arc on each side.

At around 10pm, Flight Lieutenant Avent, leading the air search, spotted something in the water.

“We altered course and flew over this, and it appeared to be a buoy, and also a long, dark object underneath the water, a dark shadow, more or less cast on the surface of the water. The shadow looked about 25 yards long and narrow, probably 2 to 3 yards wide.”

The Brazen was redirected to investigate this sighting, while the aircraft were forced to abandon their search due to the growing darkness. It would later be realised that Brazen had turned away from her grid search just before reaching the Thetis; Avent’s sighting pulled them away before they could pick it up.

News of the Thetis’ disappearance broke to the public late that night; the catering firm whose staff were on board found out when they went to Birkenhead at 10.30, expecting to meet the returning sub. An Admiralty statement was issued at around 11pm, and family members either heard it on the news, or when a telegram reached them that night.

Mrs Sybil Bolus, wife of Commander Bolus, found that telegram on her doormat when she returned from an afternoon at the cinema with a friend. There, she would have seen a newsreel carrying the story of the American submarine Squalus. Just a week earlier, Squalus had been carrying out test dives when she failed to surface. Although 26 men had been killed, divers using the McCann Rescue Chamber, a kind of diving bell, had been able to rescue 33. It’s hard to imagine what Mrs Bolus felt watching that, knowing her husband was undertaking similar tests, let alone how she felt when she learned the news that the Thetis was missing.

Like many of the relatives, she went directly to Cammell Laird’s in Birkenhead to wait for news. There, she was reported to have been “the calmest among them”, comforting and reassuring others and eventually chauffeuring many of them home to get some rest.

Back on the Thetis, two plans were being worked out. 

One was to raise the stern as much as possible. This would put the rear escape chamber closer to the surface; it appears that they had given up use of the forward escape chamber, assuming that the pain Chapman, Mitchell and Smithers had experienced using it meant that the pressure was too great there.

They pumped out the contents of three fresh water tanks, around ten tons in total, and then emptied four of the six fuel tanks. None of these tanks were actually designed to be pumped out in this way, and while a relatively straightforward workaround was available for the water tanks, the Cammell Laird’s men ended up working through the night, removing copper pipes from the main engines and bending them by hand in order to make a connection from the fuel lines to the main line pumping system.

The pump was started at around midnight, and by around 3am they had emptied a further fifty tons, and by morning the submarine would rise to about 35°. The length of the Thetis – 84m, or 275 feet – and the relatively shallow waters of that area –  around 40m, or 130 feet – meant that several feet of the stern now rose above the water. That did not, unfortunately, include the rear escape chamber hatch, which was still some 20 feet or 6m down.

The second plan would require outside assistance; securing the fore hatch from outside, so that it could withstand the pressure of blowing the water out of the forward compartments, and setting up a connection that would allow a ship on the surface to provide the high-pressure air for the procedure. 

The details of this plan were to be written out and attached to a man who would then escape using the Davis apparatus; “attached” so that the plans could still be used if the man carrying them didn’t live long enough to be rescued. To maximise his chances, they would have to wait until dawn, as even if a ship was relatively close by a single man would easily be missed at night.

However, the reality of their situation was becoming a lot more tangible as their oxygen was depleted. The hard work carried out overnight on the pumping connection meant they had used even more precious air. 

As the levels of carbon dioxide increased, it would have been the older men, and those less fit, who suffered first, but it wouldn’t take too long before all were affected. They would have had headaches so severe they caused vomiting; muscle spasms affecting various parts of the body, including the vocal cords, making speaking difficult; loss of vision, and panting for breath. Later, they might experience delusions, seizures, loss of consciousness, and finally death.

Arnold said:

“First thing in the morning everybody was struggling for breath. While I was lying down alongside another leading stoker, I asked him what he was panting for, and he said, you aren’t doing so badly yourself! I did not realise I was panting so much.”

Although the motto of HMS Thetis was “I bide my time”, Captain Oram realised that this was not appropriate in their circumstances.

“As no sign had come from the surface vessels we presumed that we had not been found, but at the same time it was apparent to the commanding officer and myself that in view of the time it was going to take to pass all the men through the escape chamber it was imperative that the escapes should commence at the earliest possible moment as there was a danger of the last men becoming unconscious before they had a chance to escape.”

Because it took about quarter of an hour for a pair of men to pass through the escape chamber and to get it ready for the next (assuming all went smoothly), it would take nearly thirteen hours for all 103 men to get out this way using only the rear escape chamber. However, the air would now be running out in around nine hours. 

With this in mind, Oram volunteered to take the plans to the surface himself. There would be some criticism over this later, but it should be remembered that, at this point, they had no idea whether there was anybody above waiting for them; and if there wasn’t, the mission was tantamount to suicide. The water temperature of Liverpool Bay in June averages around 15°C or 59°F; at this temperature, a swimmer can expect exhaustion in between 2-7 hours, and death between 2 and 40 hours, and since the men were already suffering from exposure to carbon dioxide they could expect to be on the shorter end of those timelines.

“As a precautionary measure,” Oram said later, “I called for a volunteer to come with me so that there was a chance that someone with inside knowledge would be found on the surface if I failed.”

Although Woods later admitted that he didn’t actually know what he was volunteering for, he was one of three to step up, and was chosen on the basis that he knew more about the workings of the vessel than the others.

It took the two men forty-five minutes to cover the forty feet (a little over twelve metres) up to the escape chamber, due to the steep angle of the vessel and the debilitating effects of the atmosphere, and another fifteen minutes to recover before they could climb inside. Both were smeared in thick grease to insulate them against the cold water.

One of the seamen there to work the escape chamber told Woods he had strong pains in his chest; at least one other appeared unable to get up.

“I remember estimating in my mind what was the latest period the men could hold out, and that time was six o’clock in the evening. I think I might have been probably rather optimistic.”

They waited for the water to rise around them, and activated their DSEA sets. Just as Oram opened the escape hatch, they heard a series of explosions. They were charges dropped by the HMS Brazen, a signal that they had been found. They heard the rest of the men cheering. It was sixteen hours after Thetis first went down.

This moment was, rather astonishingly, witnessed by reporters, who had been avidly following the story since it broke. Several were on board a tug named the Troon, which had left Birkenhead early in the morning to join the search. The Liverpool Echo reported:

“… we sighted shortly before 9 a.m. what we first took to be a buoy.

Our young skipper, Mr. Alfred Lamey, was puzzled, and said: “That cannot be a buoy. It is not marked on the chart.” He was right. Through the glasses it was found that what we had mistaken for a buoy slowly resolved itself into what now appeared to be the rudder and stern of an upturned submarine.

Sweeping at a wide angle from a point near the horizon, and travelling at full speed, came the destroyer Brazen, and from the opposite direction and executing a similar manoeuvre, came a large twin-engine flying boat…

As the destroyer reached the scene, to pull up full speed astern, it was observed that four of her boats were already manned and hanging from the davits, ready to be lowered. This was done, it seemed, in an instant, and from our position, barely 400 yards away, we could see the men pulling as for dear life towards the submarine. The Vigilant also lowered a launch and a pinnace followed from the Brazen. 

Suddenly two figures shot to the surface of the water and it could be seen that they were wearing the Davis apparatus. There was a shout as two of the smaller boats swung off the course and eager hands reached down to lift the men from the water.”

The Troon pulled in closer, and received a message from the Brazen by megaphone:

“We have two men on board here. They are safe, and we think all the others are alive in the submarine.”

That message was also sent to the Admiralty and Cammell Lairds; an announcement was made to the waiting families there at 8.45, and reporters were there to see their reaction.

“There were joyous scenes as the news of the men’s safety spread. Mothers, wives and sweethearts whose faces a few moments before had been lined with worry were laughing and smiling. Some of them, overcome by the relief of the tension through which they had gone, were sobbing with joy.

Mrs. Jessie Luck… the mother of Leading-Seaman Luck, of the Thetis, was among those who had waited outside the office of the shipbuilding company.

When the news came through of the safety of her son she said with tears in her eyes, “What wonderful news. Luck by name and luck by nature. Thank God.”

First news that Captain Oram was safe was conveyed to his wife at her home in Cosham, Hampshire, by a reporter.

“Naturally the anxiety has been great,” she said, “and I am very relieved at the news.”

“What about everyone else?” Mrs Oram inquired anxiously.

When told that everyone was believed to be safe she said, “That is wonderful news, indeed. I and all the other wives, I am sure, have been waiting every moment for that assurance.”

Further good news would follow; an Admiralty statement made at around 10am stated:

“H.M. submarine Thetis has been located in position 328 degrees, 14 miles from Great Orme’s Head. Her bow is in 130 feet of water and her stern is on the surface. Captain Oram, Lieutenant Woods, Leading Stoker Arnold, Mr F. Shaw, of Cammell Laird’s, have escaped by Davis escape apparatus. Captain Oram escaped to direct salvage operations and make a full report on the state of the submarine. The commanding officer and all the remainder of the crew were alive at ten o’clock and salvage equipment is being rushed to the spot.

A further statement will be issued later.”

It was also reported that an Admiralty official said; “There is every hope of getting them all out by the Davis escape apparatus.” 

Out in the Bay, Hart had already taken steps towards salvaging the Thetis. At 8.53 he sent a message to the Mersey Docks & Harbour Board: “SEND BURNERS AND BURNING GEAR OUT AT ONCE WITH TUG”.

“I think, at the time, the position in my mind was this. There was no immediate question of all the crew being lost, or indeed any of them, but as a measure of precaution and absolute necessity in the salvage of the submarine, we may require burning gear and, therefore, it is to be sent out at once.”

Later, a little after 9.30, he would signal again for gear required by Oram’s plan. Practically as soon as he got on board the Brazen the Captain had explained the plan they had come up with below, disregarding his poor state of health after his ordeal. That plan was forwarded on to the Admiralty at 9.43, and just seven minutes later a rush of bubbles in the water preceded the appearance of the second pair of escapees; Leading Stoker Walter Arnold, and Foreman Engineer Frank Shaw.

It seems that the news they carried didn’t reach the Admiralty quickly, because the statement made at ten o’clock was already wrong. Three men were already dead, and another close to it.

After Oram and Woods had escaped, the men left behind had to drain down the escape chamber to reset it. 

According to Arnold:

“…owing to the angle of the boat the water just ran over the coaming of the bulkhead door into the main motors. This caused a short circuit and there was a cloud of smoke, which came into the Stoker’s mess. We shut the bulkhead door and those that had gas masks put them on and the others used DSEA gear without being ordered to. The smoke was thick and white, and choking.”

The air had been bad enough before; now it was even worse. At this point, Lieutenant Chapman decided that the escape needed to be carried out faster.

The chamber was only 6feet 9 inches (a little over 2 metres) tall and about three feet (or less than a metre) wide, and designed for two men. Chapman decided to send four men in.

Two men from the Royal Navy, Leading Stoker Thomas Kenney and Stoker Wilfred Hole, were chosen, alongside two Cammell Laird’s men, Cornelius Smith and another who remained unnamed. It had previously been agreed that the escapes should all be paired up this way, since the Navy men had been trained to use the DSEA, and could therefore help the civilians, who had no more than a short theoretical lecture.

Arnold was one of the men operating the escape chamber for them.

“We shut the door on them and flooded up exactly as we did in the first instance. The place flooded up all right – it went in quite fast, really.”

Once the water had risen high enough, one of the Naval ratings inside was to open the escape hatch by spinning a wheel to the marked point on a dial, then removing a clip with a slight push. It would only open once the pressure was equalised. 

When Oram and Woods escaped, Arnold had seen a shaft of sunlight enter the chamber. This time, there was no light.

“We waited and waited, and it came to a quarter of an hour and still no sign of the hatch opening. Nothing happened, so we drained down, and three were dead and the other one was very near it… Their mouthpieces were just torn away from them. They were all foaming from the mouth when we brought them back. We dragged the three bodies back into the boat and helped the other chap out, and he was just about finished, when we brought the three bodies back it broke the morale of the men; you could see it on their faces. You could not speak down there – but you could see the look in their eyes.”

Cornelius Smith was just vaguely conscious. Shaw, his superior at Cammell Laird’s, knelt close, as he was trying to speak.

“I asked him why they had never got out and he said, or he tried to tell me, that they could not open the hatch.”

Either there was a fault with the hatch, or it had proven impossible to operate with four men in the confined space. It fell to Arnold and Shaw to go next. They were either about to escape, or about to die, but Arnold was confident.

“From the very first moment I was down there it never dawned on me for one minute that I was going to stop down there.”

Shaw later described their escape:

“The air was very thick before I left. I could scarcely speak because of a choking feeling round the throat. Several people were sick during the night. Leading-Stoker Arnold assisted me to put on the Davis apparatus. He reassured me on a few points on which I was uncertain. We stepped into the escape chamber together. We tried three times to lift the hatch, which opened immediately the pressure was equalised. I immediately shot out of the chamber and reached the surface in a few seconds.”

Having proved that two could still make a successful exit, both men expected to see more of their colleagues coming up. 

“I should imagine that most of the men on board the Thetis were physically able to make their escape. Those in the aft compartment when I escaped were fit enough. Arnold and I fully expected others to follow us.”

A close watch was kept for the next pair of escapees. A rush of bubbles was seen – but nobody appeared. 

Wreck master Brock said that, at this point, he heard,

“A distinct knocking, like hammering in the submarine. There was nothing continuous; it was just a case of ordinary hammering. It was purely and simply as if a man was hammering at something, and then he would stop a bit and hammer a bit more.”

More bubbles rose, again with the sound of hammering but without anyone following them. 

It would later be theorised that the next two pairs had each entered the escape chamber, but only managed to open the hatch a few inches – not enough to escape. The hammering had been their vain attempts to get it open the rest of the way. 

There were no further escape attempts, and no further bubbles to be seen on the surface.

Those above the water continued to work on the Thetis’ exposed stern, all the while keeping the immediate area clear for anyone else coming up. Ascent with the Davis apparatus was rapid, with the user often flung up out of the water, so it was important not to have anything in the way that they would collide with. The salvager, Hart, had a wire run from the Vigilant, underneath the stern of the submarine in front of her rear hydroplanes, and back to the Vigilant, as a precaution against the stern sinking again. Brock, whilst working on the hull, hammered out a message in Morse code to those inside:

“We gave repeated bangs, like an ordinary series of knockings, and there was no reply, so we spelt out “come out” a number of times so that they would know someone was waiting outside.”

Although there was no reply, and no further sign of escapes from the Davis chamber, the rescuers continued to stand back and wait for more men to surface. 

Hart, who had already arranged for the equipment necessary to cut into the hull and extract survivors, later recalled, “We were told most definitely that everybody inside was quite happy, and that they were all expected to escape from the Davis escape.”

At around 10.40, the 6th Destroyer Flotilla arrived in Liverpool Bay; a reporter from the Liverpool Echo described their arrival, as viewed from the air, in somewhat overblown terms:

“They seemed at first to come gliding towards us on a billowy carpet of white wool, a pretty picture, I thought, but it was not long before I realised how futile was the adjective “pretty.”

The picture became one of a chilling stark beauty, symbolical of pure speed and strength. It was unmistakable that these destroyers were at full speed. They cut through the water grandly and magnificently. The foam was churned in a great carpet around them and an occasional lift of their prows just added another note of the great speed at which they were travelling.”

Perhaps this padding was intended to disguise the reality of another remark in the same column; after describing the scene, with the stern of the Thetis surrounded by little rowing boats, and with the Brazen and salvage tugs standing off, the reporter wrote:

“There did not seem to be much work going on…”

Captain Nicholson, aboard the HMS Matabele, now became the senior ranking officer on site, and accordingly assumed overall command of the rescue and salvage operations. He was soon met by Woods, who was extremely concerned that no further escapes had been made in over an hour.

Nicholson would later state,

“At the time I was trying to get a grasp of the situation. Having suddenly arrived up there, I did not know what steps had been taken or what had been done. What was going to be done, and what should be done now.”

This was, of course, not exactly the clarity you’d want from the man who was now responsible for almost a hundred lives.

The plan Captain Oram had brought with him was still underway at this point. A diver named Frederick Orton had been tasked with descending to the Thetis to secure the forward torpedo hatch. This would be a very difficult task; he had only ever worked at depths of about 40 feet (12.2 metres), and the bow of the Thetis was 130 feet (39.6m) down. He had also never dived on a submarine before, and was following a rough diagram drawn by Wreck Master Brock to try and locate it in relation to the conning tower, whistle and gun recuperator.

In addition, when he began his dive he discovered a fine wire tangled all around the submarine.

“There was so much of it; there were yards and yards of it. One part came down from the buoy and that was fouled right round the conning tower, and then there were all these other bits wrapped round and round and round.”

It came from one of the marker buoys; this was helpful in marking the location of the submarine, but highly dangerous for anyone diving down to it.

Orton tied a guideline to a ladder on the side of the conning tower, then surfaced in order to get some air and avoid the need for decompression; he was the only diver available at that time, and if he worked in short bursts he would be able to work longer overall.

He made a second dive almost immediately, but couldn’t find the hatch, so he returned to the surface, preparing to make a third dive a few minutes later.

However, he was instead instructed by Brock to finish diving, and cut the ropes they were using. It was approximately 11.45.

It was at around this time that Nicholson decided to pull the stern of the Thetis higher out of the water. With the help of two tugboats, the Vigilant hauled at the submarine, bringing it up to an even sharper angle.

It was reported that some of the rescuers heard tapping from inside the Thetis at this point. When asked about it later, Nicholson said, “In fact tapping did occur… but there was too much to do. One was too occupied to follow up… we had no time. It was reported and we left it like that; I never followed it up.”

It’s difficult to think about what the men inside were going through at that time; those that were still alive, at least. Exhausted and debilitated, when the Thetis lifted without warning they were probably unable to hold on, tumbling like dice in the crowded compartments.

However, with the stern raised that bit more, Brock was able to attempt to remove an inspection plate that gave access to tank Z. In theory, once in, it might be possible to cut through the bulkhead that separated the tank from the steering compartment, and reach the men inside. At the very least, that would give them fresh air.

The outer cover was quickly removed, but when Brock turned the bolts securing the inner cover, a large amount of air blew out. The cover was quickly screwed back down again, so that they could check with Oram whether this ought to be expected. Oram said it was; but before Brock could re-open it, the Thetis swung around with the ebb tide. Brock was forced to jump clear, as the tail lost buoyancy again.

Hart later said that at this point, “It would have been possible to lash the Vigilant to the stern of the submarine and not to try to get it more out of the water.”  He advised Nicholson to hold the Thetis in this way until low tide, when they would be able to pull her higher.

“Captain Nicholson again repeated that the position was desperate and asked me if I realised it, and I told him that of course I did. He then suggested, after talking to his staff, apart from me, that we should endeavour to raise her higher, to cut this hole, by placing tugs in the reverse direction, namely, ahead of the Vigilant, and pull her up into the tide. That was his exact expression, ‘desperate’.”

This desperation came from the advice of Doctor G. Ramsay Stark, a medical adviser who arrived from Holyhead. Judging by the condition of the survivors, he had told Nicholson that the chance of anyone remaining alive after 6pm was “slight” – in contradiction to the newspapers, which had repeatedly, and optimistically, proclaimed that they had air until 1.40 am.

Hart still objected, but Nicholson was in charge; 

“I told him that I disapproved of it and would not agree to it, but if he insisted I would carry out his desire to the best of my ability, but that he must definitely assume all responsibility, as I considered that the chances were 100 to one against success, and I considered the same thing would happen as happened in the first operation, and that it might cause serious damage and lose what chance of success we had at low water.”

The towing attempt proceeded, and Hart was quickly proven to be sadly right. The wire attaching Thetis to the Vigilant snapped, and she sank once more to the bottom.

It was now just after 3pm; 24 hours had passed since her first sinking. 

When low tide arrived at around 6pm, Hart was able to pass a wire beneath the submarine from the Vigilant and up to one of the camels which were now on the scene. As the wire pulled tight, the tail rose again; until the wire snapped with a loud crack. At this point, not only did the Thetis sink yet again, but her marker buoy was also ripped away. 

The Thetis was, effectively, lost again.

According to Tony Booth, author of Thetis Down: The Slow Death of a Submarine, one or both of these incidents may have actually been due, in part, to actions from inside the vessel.

“At some point, long after all life was supposed to be extinct two men, Stoker William Matthews and one other managed to crawl into the escape chamber. Another crew member forced his concentration to close and then lock the door… The two men flooded the escape hatch and, like the two times before, they waited for the pressure to equalise. The door had again sprung open – and, again, jammed at about 3 inches up from its recess… Somebody heaved their racked body up to the door and went through the agonising process of opening it to let Matthews and his colleague back in… Unfortunately… someone forgot to close the seawater inlet. As the hatch door opened a wall of water poured into the steering compartment at a rate of about three quarters of a ton per second. Those on the engine room side of the escape chamber still had  the presence of mind to close the bulkhead door to protect themselves from the water pouring into the steering compartment.”

It was midnight before the Thetis was, once more, located. By then, one of the UK’s most experienced salvage officers had arrived; Chief Salvage Officer Thomas McKenzie had been working on raising the SMS Derfflinger in Scapa Flow. When he heard about the Thetis, on the morning of the 2nd, he had immediately offered to help, but had initially been politely rejected by both the Admiralty and Cammell Laird. It was only at around 3pm that he had been urgently summoned. 

He sent one of his divers, a man more experienced with deep diving than Orton, down to the wreck, equipped with a 4lb lump hammer. 

“My feet touched something, so it must have been the superstructure. I tapped on whatever I had hold of, I heard faint tappings; it was some distance away.”

It seemed impossible, but the diver remained certain under later questioning.

“I certainly got a response to the knocking that I gave, but whether it was a definite signal they were giving to me, I could not say because I was unable to hold myself in one position for any length of time so that I could concentrate on what I was hearing. The tide was too strong…”

However, it wasn’t possible to do any more until the tide slackened once more, and that wasn’t until around 6am on the 3rd. Two more of McKenzie’s divers went down. Again, they had orders to tap on the hull and listen for a response.

The signal came back: no sign of life.

At Cammell Laird’s office, relatives had already been told there was “no hope for the men remaining in the submarine”, with an official sadly breaking that news just after midnight. 

Undeterred, McKenzie continued to work, preparing the necessary equipment to drill into the hull and pump air in. At 12.20 they were ready to go, but he was asked to wait because Hart once more had a wire connected and was ready to lift the Thetis.

Once more, the lifting attempt failed. The opportunity had passed, and the tide was now running too fast for McKenzie to attach an airline. 

At 4.30pm, the Admiralty made another announcement.

“The Admiralty regret that there is now no longer justification for hope that any further lives can be saved from Thetis. Salvage work proceeds.”

That work would take a lot longer. There was, for a while, a campaign to leave the Thetis where she lay, as a graveyard for the 99 men entombed within her, but Prime Minister Neville Chamberlain insisted that “it was quite impossible for the inquiry to be brought to any satisfactory conclusion until the submarine had been salvaged and conditions inside the vessel had been ascertained.” She was eventually brought to the shore on Sunday the 3rd of September 1939. This news was overlooked by many, as it was the same day that England declared war on Germany. 

When the Thetis was finally brought up to the shore, a diver was the first to access the vessel; he was employed to seal some of the hatches, and attach piping to others, in order to facilitate emptying out the water inside. As he opened the engine room hatch, working by feel with bare hands, he put his hand out – and touched the face of a body which had abruptly shot upwards. The shock of this was said to have affected the diver so badly that he was in a Navy hospital for months afterwards.

That body was identified as Torpedo Gunner’s Mate Ernest Mitchell. A few days later, when salvagers actually entered the engine room, they were shocked to find more than sixty bodies, many virtually naked or with their clothes in tatters. It took more than three weeks to remove the dead from the engine room, each one wrapped in canvas, hauled out and transported to Holyhead for identification. Only a few were examined at autopsy; as soon as they were exposed to the air, they decomposed so rapidly that it was simply impractical.

From those that were examined, however, the conclusion was drawn that the men had not drowned; there was no water found in the lungs. The cause of death was recorded as asphyxiation through carbon dioxide poisoning, for all the dead. 

The first seven victims were interred with full military honours at Maes Hyfryd Cemetery, overlooking Holyhead and the Irish Sea, on the 14th of September 1939. They had to be placed in zinc lined coffins which were twice the normal size, due to the bloating. Subsequent burials there were conducted more discreetly, without a full cortege through the town, as there were simply too many.

Two exceptions were Lieutenant Commander Bolus and Cammell Laird’s engineer manager Arthur Stanley Watkinson. They were buried at sea, without any religious ceremony. 

Once the Thetis had been emptied of the majority of the dead, and the water, she was towed to Holyhead, where the remaining bodies – those in the steering room, which the divers had been unable to access – were retrieved in November. This time, specialists from the Mines Rescue Service entered through the rear escape chamber, and the job was even more gruesome. Their account stated, “It was very hot and the stench was very, very bad.” 

There were two investigations into the causes of the Thetis tragedy; the first, a confidential Admiralty inquiry chaired by Vice Admiral Robert Henry Taunton Raikes, had begun on the 6th of June, and issued its report on the 29th of June.

Raikes and the committee had decided that “there was no adequate reason for Lieutenant Woods opening the rear doors and he was not justified in doing so without instructions.” However, without any further evidence they couldn’t come to a conclusion on whether there was a mechanical failure that caused the bow cap indicator to show “shut” when it was actually open, or whether Woods had misread the indicator.

They criticised the crew for not ensuring that the eighteen clips around the torpedo tube compartment door were secured in the holders; if they had done so prior to sailing, they would have been able to shut the door more quickly.

They also criticised the men for abandoning that first door;

“If one or two men had stayed behind to make further efforts to close the door in Number Twenty-five bulkhead and had been shut in the compartment, it is probable that they would have been able to join the remainder of the crew later through the forward escape chamber.”

Nicholson’s decision to tow the Thetis by the stern was also criticised, as was Chapman’s decision to try to send four men through the escape chamber at once. The design of the escape chamber drains was noted to be faulty, “as the loose water may well fall on electric machinery and cause an electric fire.”

And they pointed out they confusion and chaos of the rescue operation:

“We cannot find anyone directing the operation at this time who had any clear idea with what object they were employing this rather drastic method of lifting the stern. There was a general impression that a hole was to be cut, but where exactly it was to be cut was not decided, and the burning gear had not then arrived.”

Lieutenant Commander Bolus was, in turn, criticised because he had blown only four out of six of the main tanks; had he blown the other two as well, the Thetis might have been found earlier, and the Cammell Laird men might not have had to work so hard – and use up so much oxygen – in rigging a line to empty the fuel tanks. The committee described this as “A costly exercise that used up a great deal of breathable air.” Presumably, he had stopped blowing the ballast tanks to preserve the compressed air which he hoped to use in blowing the flooded compartments. By the time that plan failed, the effects of carbon dioxide poisoning may well have caused him to forget that the last ballast tanks had not been blown.

The number of people on board was criticised; although it was pointed out that most had good reason to be there, “a number could have been temporarily disembarked without interfering with the effectiveness of the diving trial.”

Their conclusion, as it applied to Admiralty policy on such situations, was that: 

“We consider that experience in this case again shows that salvage operations of any kind undertaken with the object of raising a submarine, partly flooded, which is unable to come to the surface by her own efforts, and thereby rescuing her crew are most unlikely to be successful in time to save life.”

And, as far as preventing a similar incident in future, they recommended that the rear torpedo tube doors should have “a clip fitted against which the door will bear directly it is free, then if no water comes out the clip can be taken off and the door swung open. It must be impossible for the clip to be taken off until the door is free.”

These clips were implemented, and remain integral to submarine design; they’re widely known as Thetis clips, due to their origin in this disaster.

The second was a public inquiry, chaired by the Honourable Mr Justice Bucknill. One major point on which this differed from the Admiralty inquiry was that the Thetis was salvaged and investigated before they drew their conclusions. This gave them new evidence.

Firstly: “The test cock hole in the rear door of No. 5 tube was blocked by bitumastic enamel. The hole in the rear door could not be seen from inside, because the enamel was smoothed over it. The obstruction was knocked out of the hole from the outside by using the rimer.”

The enamel had been applied to the interior of all the torpedo tubes, to ensure that the torpedoes would slide out smoothly when fired. Cammell Laird were not able to undertake this process themselves, and it had been contracted out to a company named Wailes Dove Bitumastic Ltd. However, the work should have been checked by Cammell Laird and by the Admiralty Overseer. There was much debate over whether the responsibility for ensuring the test cock hole was clear lay with the painter, the Cammell Laird supervisor, or the Admiralty inspector.

The “rimer” mentioned was a simple metal rod; it was designed to be poked into the test cock to ensure that it was free from debris. Had Woods used this, he would have cleared the obstruction easily, and the test cock would have shown him that Torpedo Tube 5 was full of water. However, it was established that Lieutenant Woods had not been trained to use it as a matter of course, and since the vessel was new he had little reason to expect it to be blocked.

It’s often said that the Thetis sank because of this little blob of paint, but that’s an oversimplification; it was merely one of the factors that contributed to the tragedy.

Investigators entering the torpedo tube compartment discovered that the control levers for the bow caps on torpedo tubes 1, 3 and 5 were all at neutral, but slightly towards the “open” position, while the control levers for 2, 4 and 6 were all slightly towards the “shut” position. 

More tellingly, the mechanical indicator for the bow cap of No. 5 tube – which Woods had declared he was sure was set at Shut – was approximately at the fully Open position. The other five indicators were at Shut. However, this indicator was in a difficult position to actually see.

The control lever panel was taken away for testing, and it was found that the lever for No. 5 tube would have to be pushed a little further towards open before it would activate; therefore the control lever was in a theoretically safe position.

It was possible that somebody had, whether deliberately or inadvertently, moved the control lever to “open” and then pushed it back towards “neutral”, which would have left it open, but it was impossible to come to any conclusion.

Therefore, the question of who actually opened the bow cap of No. 5 torpedo tube – and when – remained unanswered. If it had not been opened, or if the chain of communication had been clear and Woods had known for sure that either the tube was flooded or it wasn’t, then the question of the test cock, and that little bit of enamel paint, would never have come into play.

The third factor which contributed to the sinking was the watertight door at bulkhead number twenty-five, and its eighteen clips. If it had been easier and quicker to close, the flooding could easily have been restricted to one compartment, even with Woods delaying to help Hambrook.

The inquiry also looked at the crew’s attempts to resolve the situation. They concluded that it would not have been possible for anyone to successfully close the tube door and open the two valves required to pump the water out of the flooded compartments.

Regarding the failed attempts to do just that, whilst acknowledging the danger and stress this had exposed them to, the Inquiry concluded that Chapman, Mitchell and Smithers had all experienced pain during the flooding-up process because they were not using their DSEA sets properly. The equipment was designed to be used at greater depths than that at which the Thetis lay; the pressure should not have been a problem. A later medical report, in 1956, suggested that the men had actually suffered from oxygen poisoning, caused by breathing pure oxygen from the DSEA set, and exacerbated by their prior exposure to elevated carbon dioxide.

It seems that the forward escape chamber, therefore, could have feasibly been used as an exit, halving the time needed to evacuate the vessel. 

The failure of outside assistance to save the lives of those onboard was found to be mainly due to the length of time it took to find her. Lieutenant Coltart defended his failure to raise the alarm sooner on the basis that there was not sufficient reason to believe an accident had happened; they had seen no smoke candles or indicator buoys released from the submarine, or anyone escaping from the Davis chamber.

They decided that the procedures to be adopted in the case of a submarine sinking in home waters were too elaborate, and that the decision to search for the Thetis had been delayed as a result.

The Brazen would have been able to locate Thetis immediately on reaching the area if the submarine’s ASDIC equipment had not been broken in the descent; according to the report “That was one of the many mischances which almost conspired to lose the Thetis in a sea of trouble.”

The Bucknill report didn’t make any conclusions as to responsibility for the disaster; in fact, Bucknill stated up front that he had no intention of doing so; “This Tribunal is not sitting to allocate possible blame in this matter. It is appointed to find out what happened, why, and, possibly, what can be done to prevent it happening again.”

Although legal action was taken by some of the relatives, which dragged out for some seven years, it was eventually ruled a “non-negligent accident”, for which they received no compensation.

However, some were quite clear in their opinions as to where the responsibility lay, if not for the sinking itself then at least for the loss of life. Ian Murray Taylor, the grandson of salvage officer McKenzie, said;

“He was very frustrated. He knew the loss of life was needless. If his offer of help had been taken up when he gave it and he was got down there in time he could have organised any deficiencies in the equipment and put the right stuff forward. The outcome would have been different and the delay was almost criminal.”

McKenzie had told the public inquiry how he would have conducted the rescue operation. The wire holding the Thetis up should have been attached to two vessels, not just the Vigilant, to give her stability while a hole was cut. A small air hole could have been cut to provide the survivors with air;

“If you can get fresh air into the ship, you can keep men alive for a considerable period, and the condition, according to Captain Oram’s report, was that it was only a question of hours, perhaps, twelve to twenty-four hours before the men would be dead in any case.”

On the question of cutting a hole large enough to actually get men out, he was similarly confident.

“Each hole would take about five to seven minutes to cut, quite big enough to get the men out. There is no question about the speed of the cutting. I have seen it done many times before.”

It has been pointed out that there may have been a reason for the Admiralty to avoid such action. Once the Thetis was recovered, emptied and cleaned out, she was refitted, and renamed the Thunderbolt, commissioned in 1940. Once the insurance payments claimed for the loss of the Thetis are considered, the Thunderbolt cost about £100,000 less than a new T-class build – that’s equivalent to a saving of some £6.7 million in 2021.

Had a hole been cut into the Thetis to save her crew, her hull would have been weakened, rendering the Thunderbolt less effective in war. And, Admiralty policy had been established: the ship was more important than her crew:

“A submarine is designed as a warship and whilst due consideration is given to the question of saving life in the event of an accident, it must be secondary.”

No doubt the relatives of those 99 men did not feel the same.


Thanks this episode go to:

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  • Michael Shafer
  • John Payne
  • Charlotte Fearn
  • Catherine Aitken
  • Jay Foringer
  • Elena Tyler
  • Laura Pina
  • AMW
  • Ben Douglas
  • Kylie Green
  • Sterling Hampe
  • D Brown
  • Lee Davis
  • Gloria Ambrowiak
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Sources, References and Further Reading

Wikipedia article on the HMS Thetis

Wikipedia article on the Davis Escape Apparatus

“Only Four Escaped; the sinking of the submarine Thetis” CET Warren, James Benson – archive.org

Images of the Thetis disaster – Liverpool Picturebook

Some afterthoughts on a submarine disaster – National Archives

Thetis Submarine – memorial page by Steve Johnson

Model of Thetis – Royal Museums Greenwich

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