This is the story of a unique submarine and the people who sailed in her in the Mediterranean over the course of 1941. Triumph arrived in theatre in January 1941 just as 50,000 Allied troops were being deployed to Greece to deter a German invasion. Within days of arriving this army found 200,000 heavily-armed Germans thundering towards it. A helter-skelter retreat ensued. Within sixty days both Greece and Crete had fallen, while Rommel’s Afrika Korps had arrived in Libya. Triumph was a major player before and afterwards, landing secret agents and rescuing escapers, while attacking Rommel’s supply lines and the Italian fleet with gun and torpedo. Among the many fascinating characters with whom Triumph’s tale is intertwined are the Greek smuggler Harry Grammatikakis and Lieutenant John Atkinson MC*, who was captured in Crete, escaped to Alexandria and returned to Greece as a key agent of SOE and MI9. His last return to Greece aboard Triumph ended in his dramatic recapture, trial and death by firing squad along with the key members of the Greek resistance. Tragically Triumph’s story culminates in her disappearance in January 1942, while on one last mission before a promised rest and refit. The discovery of her wreck in 2023 has allowed her final patrol and tragic loss with all hands to be reconstructed here in unprecedented detail.