After sixty-odd years the Thetis disaster has not lost its power to shock and I hope it never will. However events did not unfold in a vacuum and the disaster must be seen in the context of submarine salvage. Two earlier submarine accidents had a major effect upon Admiralty thinking; K13 and Poseidon. It is not possible to understand the decisions that were taken by the authorities in relation to Thetis, without some knowledge of these two preceding incidents.  Into this scenario we must add a third submarine accident, M2.  First it is necessary to sketch an outline of submarine rescue techniques, as they existed prior to the Thetis tragedy.

The story of submarine rescue prior to the Great War is a very short book indeed.  The grim litany of ‘A’ boat accidents demonstrates that even in cases where a submarine had been located quickly, technological shortcomings and the difficulties of raising a submarine in the open seas, meant that outside assistance was rarely (if ever) able to rescue trapped submariners. The ‘salvage blow’ remained the only tool at the trapped submariners disposal and it was not always possible to attempt this in a damaged submarine.  

 While salvage (i.e. outside help) remained the primary rescue means, some thought was given to a device which might enable submariners to save themselves by effecting escape from a crippled boat. Resources were channelled into experimentation with escape suits such as the Rees Hall helmet but the results were too bulky and there simply was not the space for storing these suits in the tiny submarines of the period. It should be pointed out that while German U boats were equipped with Drager breathing sets from 1914, British submariners had no such escape sets until 1932. Throughout the Great War, trapped British submariners simply died without entertaining any hope of escape.  However there were exceptions. Now we must briefly examine what was possibly the most successful submarine escape in British maritime history.

There are stunning parallels between the sinking of K13 and the Thetis incident. Both vessels were on diving trials, both submarines carried a large number of shipbuilders in addition to their crew.  There is one important difference which should be noted from the outset however, whereas Thetis sank in the open waters of Liverpool Bay , K13 made her dive in the enclosed waters of the Gareloch.  K13 (Cdr Godfrey Herbert) made her fateful dive on 29th January 1917 .

An engine room ventilator intake was mistakenly left open. As the boat dived at 1510, the engine room flooded resulting in the deaths of all within the stern compartments. Forty-eight men were trapped in K13 (it will be recalled that Thetis contained one hundred and three men). The boat lay stern-down in 55’ of water. (Thetis lay in 150’ but was later raised to a few feet beneath the surface) It was late January and Cdr Herbert recognised that the trapped men could not expect any assistance until dawn at the earliest.  Now, it was extremely fortunate that a second submarine E50 (Lt Cdr K Michell) was also carrying out trials in the Gareloch at this time.  The crew of E50 witnessed bubbles rising to the surface and at 1600, Michell raised the alarm.  Just after midnight two salvage vessels arrived. In the meantime, Michell and his crew worked feverishly, searching with lead lines.  At 0200 on the following morning, K13 was found.  At 0800 on the 30th January the first diver went down.  As the day dragged on, it became apparent that the trapped men were increasingly suffering from carbon dioxide poisoning.

 Herbert feared that Admiralty would prioritise saving the submarine above rescuing the trapped men.  He planned to send a volunteer to the surface in order to direct rescue efforts.  That volunteer was fellow submarine commander, Lt Cdr Goodhart and at midday on the 30th, he made his escape bid with the help of Herbert.  Again the parallels with Oram of Thetis, are striking.  However matters went tragically wrong, Goodhart was killed and it was Godfrey Herbert who was accidentally propelled to the surface. His first words on regaining his senses were, ‘Air…give them air…right now’.  E50 had been equipped with a 5” high-pressure airline. By 1500 it was already dark and the divers were uncertain as to where the air line should be fitted.  The submariners set about instructing them. As the crew of E50 worked on throughout the night, Michell and Herbert listened to the plaintive hull tapping through their hydrophones, ‘GIVE US AIR, GIVE US AIR, GIVE US AIR…’

At 1800 on Tuesday 30th January, the divers found the valve they were looking for.  The HP air line was duly fitted into a valve in the gun ammunition hoist by the divers. However partly because the line became blocked by ice and partly because of the debilitation of the trapped men, the transfusion of air did not take place until 0155 on Wednesday 31st January. By this stage the men had been trapped for thirty-five hours. Divers and submariners had worked to the very limits of human endurance but their efforts had paid off. Michell in particular had taken command of the situation. He had argued, bullied and pleaded with the divers until the airline was in place. 

This was not the end of the K13 story.  An argument now developed between Michell  (who advocated hauling the bows up as quickly as possible, then cutting through the fore-ends) and Captain Young who favoured an approach more protective of the submarine pressure hull.  The Fairfield technicians (and the boat officially belonged to Fairfields rather than the Royal Navy) favoured a slower, more methodical approach. It should not surprise us that such arguments took place. There was simply no precedent for a submarine rescue at this time. The Admiralty Naval Salvage Advisor, Captain Frederick Young, cast the shadow of an eminence grise over the K13 affair. Cdr Godfrey Herbert:

We had great altercations. Captain Young said it would be an example of bad salvage to damage the hull but that by continuance of the lifting operation we should be able to raise the boat high enough for the men inside to get out through the torpedo loading hatch. This was to me highly improbable and I do not think it could have been done…”

Again we have parallels with some of the accusations that later raged over Thetis. Certainly Herbert and Michell believed that sections of the Admiralty not only knew little about submarines, they were indifferent to the fate of the trapped men.  Both Herbert and Michell had agreed a pact that placed saving the trapped men above their personal career prospects. In the face of opposition from Captain Young, the Fairfield technicians and divers agreed to fix hawsers and haul the bows out of the water. Additional airlines were attached to lighten the fore-ends of the submarine. By 2100 on the 31st January, the bows of the submarine were just above the surface. A welder attempted to cut a manhole with the waters of Gareloch lapping around his boots.  Then a cry went up, ‘We’re in!’

After spending a staggering fifty-six hours trapped on the bottom of Gareloch, despite the muddle, despite the confusion and the argument, all forty-six men were rescued.

Where does all this get us?   Outside salvage worked as long as suitably equipped vessels were at the scene quickly enough.  An injection of HP air will keep trapped men alive, until rescue can take place. The K13 rescue also demonstrated that the expertise and guidance of submariners was invaluable.  It might be thought that lessons learned from the K13 rescue might have been codified in the form of guidance notes or training programs for salvage teams or submariners but the event was simply forgotten. No exercises were carried out to determine how long it would take salvage ships to steam out to the site of an accident.  The entire subject of submarine rescue remained taboo in both submarine and general service.

Locating a crippled submarine proved the most difficult task in the 1920s. L24 in 1924 and M1 in 1925 took their last dives without a single survivor.  Bad weather prevented the location of the former while the latter was simply too deep. By November 1929 a handful of submarines was equipped with the new Davis escape set or DSEA.  The DSEA set contained a small high pressure air cylinder containing sufficient oxygen for thirty minutes – if used sparingly. (DSEA also incorporated a drogue skirt to slow down ascent to the surface and thus guard against ruptured lungs). The first real test of DSEA came in June 1931, with the sinking of HMS Poseidon off Wei hai Wei, the China station.

To cut a long story short, Poseidon was accidentally rammed by a Chinese vessel. Thirty men managed to scramble out in time but the boat sank to 130’, taking eight men with her. The boat was equipped with DSEA although specialised flooding valves were lacking.  Eight men  managed to leave the boat. Two failed to reach the surface and one of the escapees later died.  The implications of successful DSEA escape were to mould Admiralty thinking over the next decade.

In 1931/32 Admiralty introduced the policy of Subsmash.  Firstly, organisational procedures were tightened up. A submarine engaged on exercises was required to transmit details of diving time and location to Fort Blockhouse , Gosport . In the event of a submarine failing to surface, Blockhouse would transmit the code Subsmash throughout the Royal Navy, thus triggering a massive search in the last known position of the submarine.  The cornerstone of Subsmash was an assumption that, with the advent of DSEA, a trapped submarine crew held salvation in its own hands.  All British submarines were now modified to incorporate escape hatches equipped with either collapsible canvas trunks (twill trunks) or two man escape chambers. Fast flood valves were also fitted.  Explicit instructions were now issued to submarine skippers.  A trapped crew must no longer wait for outside assistance in the event of an accident, rather it must revert to DSEA. Subsmash made no provision for salvage.  Existing valves designed to be fitted with HP air hoses from salvage vessels in the event of an accident, were sealed off (Shelford ‘Subsunk’ p 61). It was not long before the shortcomings of this new policy were to be cruelly exposed.

M2 had been the first British submarine to be fully equipped under the new Subsmash policy. The sixty-strong crew were trained in its use, indeed AB Morris had been one of the POSEIDON survivors. On 26th January 1932 the boat went missing while on exercise in West Bay .  M2 could not be located in time and there were no survivors.  When she was found eight days later, M2 was upright (albeit with her bows at an angle), her stern embedded in the seabed, in a depth of 106’. Forensic evidence suggests that the hangar door was opened prematurely following a dive.  Water cascaded in through an open hatch within the hangar, inundating the boat.  It is possible that some men remained alive, trapped within the submarine, yet there was not the slightest indication of any attempted DSEA escapes in otherwise favourable conditions.  It is not unreasonable to speculate that any survivors were too debilitated by carbon dioxide poisoning to make an escape.  At any rate, here was evidence that DSEA was not the panacea it promised to be.  Far more than DSEA was required to guarantee saving a crew.

When Fort Blockhouse became aware that Thetis was missing at 1820 on 1st June 1939 Captain Macintyre, acting CO in the absence of Captain Oram (who was of course trapped in Thetis) transmitted code 971/35 Subsmash throughout the Royal Navy. A massive sea an air search unfolded.  Although three flying boats were allocated to the operation and landed at Holyhead, crucially no attempt was made to fly in the elite Royal Navy divers on exercises at Inveraray with the specialist diving vessel, HMS TEDWORTH.  These divers were acquainted with working in depths of 300’. TEDWORTH weighed anchor, unfortunately she was forced to head for the Clyde to bunker coal before making the journey to the Mersey .

Meanwhile at 0255 on the 2nd June the Mersey Docks and Harbour Board salvage vessel, VIGILANT (Captain H Hart) responded to calls from Admiralty and sailed for the scene.  Until the closing stages of the drama, VIGILANT would be the only salvage vessel present. She was poorly equipped for the role she was about to play.  She carried no compressor, only a hand pump dating from the 1890s.  This hardly mattered because the short length of high pressure air line she carried, would never reach the submarine lying in 150’.  Evidence from the diary of Rear Admiral (S) Bertram Watson suggests that Admiralty were unaware just how ill-equipped VIGILANT actually was.  There is no indication that any checks were made as regards the capabilities of this vessel.  The one advantage that the vessel has was that Captain Hart, as Marine Surveyor, knew these waters better than anyone.

At 0754 Thetis was located. It is of crucial importance for the reader to understand that Rear Admiral (S) Bertram Watson immediately requested that Admiralty send salvage pontoons known as ‘camels’ to the scene without delay.  We now know that Admiralty failed to respond to this request. An impressive array of vessels now converged on the position.  Who was in overall charge?   Subsmash laid down that the officer commanding was the senior officer at the scene, in this case Lt Cdr Mills of BRAZEN. Submarine experts Rear Admiral Bertram Watson and Captain Macintyre were in transit on HMS WINCHELSEA. There had been no attempt to fly them from Lee on Solent to Speke.  Lt Coltart was already being held responsible for the delay in finding Thetis and so was not consulted.  No attempt was made by those in authority to consult, the pool of submarine expertise in Birkenhead and Barrow.



Instead, Mills followed the Subsmash procedures to the hilt. All vessels but VIGILANT were kept away from the stern in readiness for DSEA escapes from THETIS.  Lt Cdr Mills was not thinking in terms of salvage and so did not send for a second, better-equipped vessel.  When Captain Oram and Lt Woods made their DSEA escape at 0800 the Subsmash policy seemed to be paying off.  Despite being debilitated by carbon dioxide poisoning, Oram further warned Mills to keep his warships away from THETIS in preparation for more DSEA escapes. Captain Nicholson of the 6th Destroyer Flotilla arrived at 1040 to take over command of the operation from Lt Cdr Mills. It is impossible not to feel sympathy for Nicholson.  Now in overall command of a desperate situation, rapidly spiralling out of control, by his own admission, Captain Nicholson knew little about submarines. He found himself directing an operation which required the active co-operation of civilians who had no intention of unquestioningly obeying orders. All Captain D (6) could do was follow Subsmash guidelines.


By this stage Hart realised the true state of affairs and concluded that the trapped men must be incapable of escaping with DSEA. Only salvage could save the men now.  At 0855 he sent this message back to Liverpool Docks:


Oram had brought a message from Lt Cdr Bolus containing instructions for attaching an HP line. Valve locations were given together with an imperative to attach strongbacks to the forward torpedo loading hatch.  It was clear that at the time this message was penned, Lt Cdr Bolus was seeking to carry out a ‘salvage blow’ - i.e. an injection of high pressure air, used to force water out of the flooded compartments.  Bolus could then harness the air in the tanks to blow Thetis back to the surface. The torpedo loading hatch posed something of a problem in that it had been designed to withstand external rather than internal pressure, hence the imperative to fix strongbacks. It is evident that all concerned underestimated the debilitating effects of carbon dioxide. Confirmation of the now desperate conditions within the submarine came at 0955 when Stoker Walter Arnold and engine fitter Frank Shaw made their escape. Given that a salvage blow would have required the active participation of the trapped men, Captain Hart realised that it was too late to consider this option. Only an immediate transfusion of air could save the trapped men now.


A diver was required to fix an air line. The reader should be aware that the vicious tides of Liverpool Bay meant that only two narrow windows of opportunity were available, one just before high water at 1130 and the other at 1730.  Thetis contained sufficient air to sustain life until 1500, therefore the afternoon slot would be too late for the trapped men.  Everything depended upon the inexperienced Frederick Orton’s 1130 dive.  The diver did his best but he had never been deeper than 90’.  Orton, unfamiliar with the layout of a submarine, failed to locate the two valve positions indicated in the note from Bolus. 



The trapped men were clearly too debilitated to escape using DSEA. The opportunity to fix an air line had been missed. Only one avenue of potential salvation remained.  By cutting into the exposed stern, it might be possible to puncture the stern bulkhead and attach an airline directly.  Hart faced four fundamental problems. Until Crosby arrived from Liverpool Docks, he had neither the appropriate cutting gear, nor the requisite length of high pressure air line and compressor.  As was explained earlier, none present knew much about submarines. No attempt had been made to supply Captain Hart, Diver Fred Orton or Wreck Master Charles Brock with a ‘T’ class submarine blueprint.  Stern ballast tanks could be expected but it was impossible to predict whether they would contain water. Finally, the tide was turning against the operation. So far the tides of Liverpool Bay had supported the exposed stern.  Captain Hart knew that from noon , these tides would conspire to force the stern back under the surface.  At 1330, without the benefit of burning gear, Wreck Master Brock attempted to unscrew a manhole on the submarine’s stern.  The manhole was removed to reveal a second cover beneath.  This was indeed the cover of ‘Z’ tank. Beyond this tank lay the pressure hull. As Brock commenced to remove the bolts, a terrible scream of escaping air, alarmed all present.  Brock was already perched in a precarious position astride the frequently dipping stern. The tide began to tug at the stern. As it started to cant over, Hart ordered Brock off the stern for his own safety.

At 1430 Crosby appeared (five precious hours had elapsed since Captain Hart had first sent his message).   It was estimated that Thetis contained sufficient oxygen to support life for only thirty more minutes. Now a dispiriting difference of opinion arose amid the rescuers. Captain Nicholson, desperate to save the trapped submariners, urged that the stern of Thetis should be hauled out of the water to allow Brock to continue with his cutting work.  Captain Hart warned against placing too much strain on the supporting cables in the face of a hostile tide.  It should be remembered that there was no precedent for this operation, no guidance, no procedure notes. Nicholson recognised the risks but this was the last remaining hope of saving the men.  One fundamental point must be understood in relation to what transpired. Because of the absence of camels, the stern of Thetis had never been adequately secured (although Hart had ordered camels from Liverpool and Glasgow Salvage Association and from Mersey Docks that morning, they did not actually arrive until 1745).  It has been suggested that Thetis could have been lashed to a couple of Tribal class destroyers, and then beached in shallow water.  It must surely be observed that if Thetis could not be adequately supported by Vigilant and Crosby, the chances of the submarine remaining attached to a couple of fast destroyers steaming through the tides of Liverpool Bay , were not high.  Others have suggested that blowing the stern off the submarine using explosives may have saved the men.  The effect of an explosion on a submarine quite literally hanging by a thread, might well be imagined. 

The stern was hauled out, inch by inch until the dripping screws emerged. Then, at 1510, catastrophe. Captain Hart’s predictions proved all-too accurate as the supporting cables snapped under the strain.  The stern of HMS/M Thetis spiralled, then slipped away beneath the surface.  It is now known that some of the trapped men survived until at least midnight , but the slipping of the stern marked the effective end of any hopes of rescuing them.

So there we have it.  K13 showed that salvage could save lives.  Following the partially successful escape from Poseidon, Admiralty placed total reliance in the DSEA set, despite the evidence surrounding the loss of M2, which, at the very least, raised doubts over DSEA as the solution to the problems of submarine rescue.  Salvage and salvage equipment played only a minor role in Subsmash operations, as Admiralty understood them from 1932.  With the advent of DSEA, a crew had its means of salvation within its own hands.  And so it was that when Admiralty learned that Thetis was missing on the afternoon of 1st June, no attempt was made to procure these ubiquitous salvage pontoons from the Mersey and tow them out to the vicinity of the submarine’s dive.   More damning still was the failure of Admiralty to respond to the urgent request of Rear Admiral (S) for camels at 0753 on the morning of 2nd of June.  Had these pontoons been available to support Thetis, it is perfectly possible that Charles Brock could have had a steady platform to cut through ‘Z’ tank, prior to penetrating the steering compartment beyond.

The author concludes that no individual should be blamed for the Thetis disaster. The abundant failings were systematic and institutional. In the final analysis, the Thetis victims were not murdered by a ruthless Machiavellian Admiralty which prioritised preserving the integrity of the submarine pressure hull above rescuing the men trapped within, rather they perished because their lives had been entrusted to an incompetent naval hierarchy, operating an inadequate system of submarine rescue.


Copyright P Armstrong 2006