The Royal Navy’s T-class submarine HMS Thunderbolt has the dubious distinction of sinking twice with nearly all hands on board. Originally to be named HMS Thetis (N25), the boat sank before officially being handed over to the Royal Navy during a dive trial in Liverpool Bay, England on June 1, 1939.
The incident occurred after the inner hatch on a torpedo tube was opened while the outer hatch to the sea was also open, flooding the submarine in the process. That small error resulted in a high loss of life, but it was just one of several problems that had to be resolved with the T-Class submarines.
HMS Thetis was salvaged and returned to service.
Recommissioned as HMS Thunderbolt in 1940, the vessel took part in combat operations during the Second World War, until she was sunk by an Italian corvette on March 14, 1943, with all hands on board.
Uncertain Beginnings
The boat, which had been built by Cammell Laird in Birkenhead, England, was launched on June 29, 1938, only a year before its faithful accident.
On June 1, 1939, the boat was conducting a trial dive in Liverpool Bay, and in addition to her 53-man crew under the command of Lieutenant Commander Guy Bolus, HMS Thetis was also carrying technical observers from Cammell Laird along with naval personnel from the Admiralty, including Captain H.P.K. Oram, commander of the Fifth Submarine Flotilla.
A total of 103 men were on board, but when the first dive was attempted at about 14:00 hours, it was determined the submarine was too light.
A survey of the six bow torpedo tubes was checked – and it was determined that while Numbers 1 to 4 were correctly found empty, Numbers 5 and 6 were tested to confirm that each contained seawater. When not used for shooting torpedoes, those two tubes could be employed as ballast tanks.
The test cock of the Number 6 tube squirted water, indicating that the tube was flooded, while a subsequent test of Number 5 did not. A combination of bad luck and human error resulted in tragedy.
Apparently, some enamel paint had blocked the flow of water to the valve on the Number 5 tube, though the outer door (bow cap) was open. It remains unclear why that bow cap was open, but it was likely a malfunction.
There was also confusion among the crew due to the fact that the “Shut” position for tube 5 on the dial was the mirror image of Number 6. This was simply a counter-intuitive design that proved to be a recipe for disaster. Lieutenant Frederick Woods, the boat’s torpedo officer, opened the hatch to confirm the tube was empty, and in doing so water rushed in.
HMS Thetis quickly sank to the seabed 150 feet (46 meters) below the surface.
The crew reportedly didn’t initially panic, as the T-class was designed with six compartments. However, it proved more difficult than expected to close the watertight doors that separated the torpedo room from the stowage compartment. The Royal Navy’s submarine at the time didn’t feature the quick-locking door with a wheel, instead, each door had some eighteen butterfly bolts around the edge that needed to be closed in an emergency.
That was another design flaw that prevented the doors from being closed.
Matters were made worse by the fact that the torpedo stowage compartment was set up for a special lunch for the visiting dignitaries and was full of extra furniture and loose equipment that impeded the crew’s escape. Just four sailors managed to make it to the escape hatch, while the boat became a tomb for the remaining 99 men on board.
The tragic sinking eventually led to the redesign of all torpedo tubes on British and Australian submarines.
A latch, known as a “Thetis clip,” was added to the inner tube door so that it could be fractionally opened to check that the tube was not open to the sea before being fully opened. It should be added that there is some irony that Thetis was a name taken from Greek mythology – the mother of Achilles. The Thetis clip was meant to address an existing “Achilles Heel” flaw with the Royal Navy’s submarines.
Returned to Service and Lost Again
HMS Thetis was eventually salvaged, and repaired. Then to avoid any suggestion of a “jinx” on the boat, she was commissioned HMS Thunderbolt as an epitaph to her “previous life.”
However, it has been noted since that the two previous vessels named HMS Thunderbolt had also been lost in crashes. The fact that a rust line remained on the walls of the sub from the original sinking probably didn’t sit well with the crew either. However, she entered service with the Royal Navy in November 1940 and was deployed in the Atlantic and Mediterranean theaters of operation.
Though the boat initially had a successful career, helping to sink an Italian submarine in December 1940, and then aided in sinking an Italian light cruiser and supply ship in early January 1943, the crew’s luck ran out on March 14, 1943. While attacking the transport Esterel off the coast of Sicily, the submarine was subsequently hunted by the Italian corvette Cicogna. The small surface combatant was under the command of a former Italian submarine captain, who also knew the local waters.
Struck by multiple depth charges, HMS Thunderbolt sank in 4,430 feet (1,350 meters) of water, with the loss of all hands. To this day, the exact location of the submarine remains unknown.
The Royal Navy’s HMS Thunderbolt was just one of two submarines that had previously sank and returned to service during the Second World War – with the other being USS Squalus, later USS Sailfish. In addition, several U.S. warships were returned to service after the attack on Pearl Harbor.
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A Senior Editor for 19FortyFive, Peter Suciu is a Michigan-based writer. He has contributed to more than four dozen magazines, newspapers, and websites with over 3,200 published pieces over a twenty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. You can follow him on Twitter: @PeterSuciu.
Note: The image is of a British S-Class Submarine. Sadly a T-Class Submarine photo that would format properly was not possible as of publication.
