Thetis Down: The Slow Death of A Submarine

Reviewed by Ingo Heidbrink

Maritime disasters are regularly topics catching the attention of maritime interested readers, authors, the media, historians and so on. The loss of HMS Thetis in 1939 was no exception to this rule. It had substantial coverage by the media in the immediate aftermath of the tragic event as well as a small number of naval historians analyzing the event throughout the decades to follow. Nevertheless, the outbreak of World War II overshadowed the tragic events of summer 1939 more or less completely, and even people with a decent knowledge of submarine history might have never heard about the loss of HMS Thetis.

Tony Booth’s book adds to the existing historiography on the loss of HMS Thetis. Thus the first question to be asked is if it is just another iteration of a known story or if it brings new details or a new perspective to the table. The short answer to both questions is a definite ‘yes’, but prior to discussing Booth’s specific contribution to the historiography, it might be useful to do a short recollection of what actually happened. HMS Thetis was one of the most modern and advanced British submarine designs when its keel was laid in December 1936. Launched in summer 1938 the submarine was scheduled for its diving tests in 1939 with disaster already looming at the horizon. A first set of sea-trials needed to be abandoned due to some substantial mechanical issues like the steering gear operating in the opposite direction as indicated and issues with the diving planes. Once these problems where fixed the HMS Thetis set sail for its last and fatal voyage. During this trial voyage additional observers and navy official were aboard even when the diving tests started. Initially Thetis could not submerge, and it was checked if the diving cells and torpedo tubes were flooded. As the test-cock for one torpedo tube was blocked due to some paint that was wrongly applicated, the crew thought the tube would be dry and forced it open just to realize that it was flooded and, as the outer door of the tube was open too, the boat was immediately flooded. While the boat sunk to the ground, the crew managed to escape to the aft sections of the Thetis and to isolate this section from the water flooding into the boat. Due to the more than normal number of crew, increasing CO2 levels became an issue and the crew needed to abandon ship through the one usable escape hatch as quickly as possible. As the crew tried to max out the number of crew escaping through the hatch each time and due to some design flaws of the escape hatch (outer hatch of the chamber could only be operated from inside the chamber and not from inside the boat) the escape became inoperable after some men managed to get to the surface. All outside attempts to rescue the men still trapped in the boat failed and when Thetis was finally salvaged, only the dead corpses could be retrieved. The boat was finally recommissioned in 1940 as HMS Thunderbolt with all references to the boat being the original Thetis removed.

While Booth’s chapters on the actual loss of the boat are definitely a worthwhile read, the real strength of the book are the chapters dealing with the aftermath of the accident, like the retrieval of the bodies, the Board of Inquiry, the public tribunal and the fights over the findings of the inquiry and the tribunal. Even more interesting is to read how Nazi propaganda used the Thetis accident for a 1943 radio docudrama broadcasted in Germany and written to showcase the irresponsible behavior of the British Admiralty. The loss of the Thetis also directly resulted in certain safety improvements like the so-called ‘Thetis-clip’, that prevents the immediate full opening of the inner door of a torpedo tube and thus limits the volume of water flooding in if a flooded tube is opened, which should not be possible at all, but Thetis had shown this could indeed happen.

Despite of Booth’s meticulous research it needs to be noted that there are no footnotes or individual references in the book, but just a short bibliography and a list of archival sources at the end of the book. While this might not be a big issue for the majority of the readers, it is a major drawback for any serious historian as individual statements cannot be verified against the sources. At least a detailed index compensates a little for the lack of individual references when it comes to the usefulness of the book for future naval history research and as a reference book. Another criticism that needs to be noted is the comparably poor reproduction quality of the 40 historical photographs and illustrations included with a good number of details obscured in shades of gray instead of crisp black and white. Even for a book with a low retail price it should have been possible for the publisher to provide a better reproduction quality.

When thinking about a recommendation to conclude this review, the first thing that comes to mind is that Thetis Down is a book that will definitely find its place on the bookshelves of naval history buffs and anyone interested in submarines. In addition, it is a book that tells a cautionary tale on how minor technical details can cause ultimate disaster, and thus should be recommended to everyone who is involved in critical construction and/or maintenance processes of submarines and comparable systems where the slightest mistake can easily turn into a matter of live or death for huge number of crewmembers. For the professional historian the book might serve as a nice little compendium on one of the most overlooked naval disasters in peace-time, but will remain a certain disappointment due to the lack of proper detailed references and thus the ability of the book to serve as a springboard to future research. Regardless, given the comparable low cost of the book, this reviewer ultimately recommends the book to the amateur as well as to the professional historian with an interest in submarine history. 


Booth, Tony. THETIS DOWN: The Slow Death of a Submarine. Pen & Sword Maritime 2019.

Reviewed by Ingo Heidbrink, Old Dominion University, Norfolk, VA (USA).

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