HMS Thetis (N25)

HMS "Thetis" was a Group 1 T-class submarine of the Royal Navy which served under two names. Under her first identity, HMS "Thetis", she commenced sea trials on 4 March 1939. She sank during trials on 1 June 1939 with the loss of 99 lives. She was salvaged, repaired and recommissioned as HMS "Thunderbolt" serving in the Atlantic and Mediterranean theatres until she was lost with all hands on 14 March 1943. [cite web | title=HMS Thunderbolt (N 25) | work= uboat.net | url=http://uboat.net/allies/warships/ship/3485.html | accessdate=2007-01-06] This makes "Thetis" one of the few military vessels that have been lost twice with her crew in their service history, like the "H. L. Hunley".

HMS "Thetis"

"Thetis" was built by Cammell Laird in Birkenhead, England and launched on 29 June 1938. After completion, trials were delayed because the forward hydroplanes jammed, but eventually started in Liverpool Bay under Lieutenant-Commander Guy Bolus. "Thetis" left Birkenhead for Liverpool Bay to conduct her final diving trials, accompanied by the tug "Grebecock". As well as her normal complement of 59 men she was carrying technical observers from Cammell Laird and other naval personnel, a total of 103 men. The first dive was attempted on 1 June 1939 at about 14:00. The submarine was too light to dive, so a survey of the water in the various tanks on board was made. One of the checks was whether the internal torpedo tubes were flooded.

Lieutenant Frederick Woods, the torpedo officer, opened the test cocks on the tubes. Unfortunately, the test cock on tube number 5 was blocked by some enamel paint so no water flowed out even though the bow cap was open. This combined with a confusing layout of the bow cap indicators - they were arranged in a vertical line with 5 at the bottom - 1,2,3,4,6, and then 5; and the shut position for tube 5 on the dial was in a different position to the other torpedo tubes - led to the inner door of the tube being opened. The inrush of water caused the bow of the submarine to sink to the seabed 150 feet below the surface.

An indicator buoy was released and smoke candle fired. By 1600 "Grebecock" was becoming concerned for the safety of "Thetis" and radioed the HMS Dolphin submarine base at Gosport. A search was immediately instigated. [ [http://www.rnsubmus.co.uk/general/losses.htm Submarine losses 1904 to present day] , RN Submarine Museum, Gosport] Although the stern remained on the surface, only four crew escaped before the rest were overcome by carbon dioxide poisoning caused by the crowded conditions, the increased atmospheric pressure and a delay of 20 hours before the evacuation started. Ninety-nine lives were lost in the incident. In addition to the normal crew of 53, there were 26 Cammell Laird employees, another 9 naval officers, 4 Vickers-Armstrong employees and 2 caterers. The crew waited before abandoning the vessel until it had been discovered by "Brazen", a destroyer which had been sent to search for it and which indicated her presence by dropping small explosive charges into the water.

The incident attracted legal action from one of the widows, who brought a claim of negligence against the shipbuilders, for not removing the material blocking the valve. [Duncan v Cammell Laird [1942] AC 624] Unfortunately for her the Admiralty successfully invoked Crown Privilege (now termed Public Interest Immunity) and blocked the disclosure of, amongst other items, 'the contract for the hull and machinery of Thetis' as evidence in court, on the basis that to do so would be 'injurious to the public interest'. [Roberts, David " HMS THETIS - Secrets & Scandal"] The case is one of interest in English law, as the judges in this case accepted the Admiralty's claim on face value with no scrutiny, a ruling later overturned.

One further fatality occurred during salvage operations, when Diver Petty Officer Henry Otho Perdue died from "the bends" on 23 August 1939. On Sunday 3 September "Thetis" was intentionally grounded ashore at Moelfre Bay, Anglesey. It was the same day that war was declared. Human remains that had not already been removed by the salvage team were now brought out to a Naval funeral, with full honours.

The "Thetis" disaster was in marked contrast to the successful rescue of the survivors of USS "Squalus", which had sunk off the coast of New Hampshire just a week previously.

In 1997 BBC Radio 4 broadcast a radio play about the Thetis disaster. The play was called "Close Enough To Touch" and was written by Liverpool writer Fred Lawless. The play was also broadcast on BBC Radio Merseyside and the BBC World Service. In 1999 a play entitled 'HMS Thetis' by Mark Gee in association with David Roberts, was performed at the Liverpool Bluecoat Chambers and at Birkenheads Pacific Road Theatre.

HMS "Thunderbolt"

The submarine was successfully salvaged and repaired, being commissioned in 1940 as "Thunderbolt" under the command of Lt. Commander Richard Crouch.

During the next 18 months she saw service in the Atlantic: In December 1940 she was on patrol in the Bay of Biscay and on 15 December she encountered and sank the Italian submarine "Tarantini".

In the autumn of 1942 "Thunderbolt" was converted with her sister ships "Trooper" and "P311" to carry two "Chariots" (a type of manned torpedo) and their crews for operations against Axis shipping in harbour, and was transferred with them to the Mediterranean in December 1942.

Their first mission, Operation Principal, was undertaken in December 1942, the three boats taking their charges to targets around the Mediterranean. "Thunderbolt"'s objective was shipping in Cagliari, but the operation was not a success, and "P311" was lost at La Maddalena, her intended target.

A second operation against Palermo harbour in January 1943 was more successful. On the 2-3 January the manned torpedoes entered the harbour and mined the ships there, sinking the cruiser "Ulpio Traiano" and the freighter SS "Viminale".

A further mission to Tripoli harbour took place on 18 January. This was to prevent the Axis using blockships to neutralize Tripoli harbour, which was about to be occupied by the British Eighth Army.

"Thunderbolt" was sunk on 14 March 1943 off Cap St Vito by the Italian corvette "Cicogna", [Colledge. Roskill has "Cicogno"; but see ] which had detected her and attacked with depth charges. All hands were lost and the sub settled to the bottom in 1,350 metres of water.

The Thetis Clip

The torpedo tubes on British submarines were afterwards equipped with a "Thetis clip", one of the modifications introduced as a result of the accident. This is a latch which allows a torpedo tube door to be opened no more than a small amount in case it is open to the sea at the bow end. Once it is clear that no flooding will occur the latch can be released and the door fully opened.

External links

* [http://www.nationalarchives.gov.uk/catalogue/displaycataloguedetails.asp?CATLN=6&CATID=8752967&SearchInit=4&CATREF=ADM+298%2F499 Report on the events surrounding the Thetis disaster of 2 June 1939 held at the National Archives of the United Kingdom]

ee also

* List of United Kingdom disasters by death toll
* List of wars and disasters by death toll (worldwide)
* List of disasters (by subject)
* Public Interest Immunity - the litigation over the accident played a key role in development of the law

Notes and references

*Stephen Roskill, "The War at Sea 1939-1945" Vol II (1956) ISBN (none)
*"Submarines, War Beneath the Waves, from 1776 to the Present Day", by Robert Hutchinson ISBN 978-0060819002
*Colledge
*C.E.T Warren & James Benson. "The Admiralty Regrets...the Disaster in Liverpool Bay" (Avid Publications 1997) ISBN 0 9521020 8 0
*David Roberts." HMS THETIS - Secrets & Scandal - Aftermath of a Disaster" ( [Avid Pubications - ISBN 0 9521020 0 5) 1999
*"Close Enough To Touch", radio play written by Fred Lawless for BBC Radio 4 and the BBC World Service 1997
* HMS Thetis - a play by Mark Gee in association with David Roberts. 1999