The submarine HMS Seraph carried out a calculated deception operation known as Operation Mincemeat, designed to mislead the Axis powers regarding Allied plans. In late April 1943, the British military sought to divert German attention from the upcoming Allied invasion of Sicily by suggesting that their targets were elsewhere, particularly Greece. To execute this ruse, they employed a corpse to be presented as a British officer carrying fake documents indicating an impending operation in Greece.

Major William Martin, a Royal Marine whose identity was fabricated for the operation, was chosen as the 'courier.' His body was dressed in a uniform, and false papers were placed in a briefcase that included detailed and fabricated details of the supposed invasion plans. The HMS Seraph submerged off the coast of Huelva and released the body into the tidal currents. The idea was that the body would wash ashore, be discovered by German naval officers, and consequently lead them to believe in the falsified invasion plans.

Once the body was found by local fishermen, it was turned over to the authorities, who recognized the significance of the documents on the corpse. German intelligence promptly acted on the information, leading to a reassignment of forces that inadvertently facilitated the actual Allied invasion of Sicily. The success of this operation significantly impacted the course of the war, as it effectively diverted German resources and attention, illustrating the power of deception in military strategy.