The barrister F. Ashe Lincoln was a sub-lieutenant in the Naval Reserves when he was called to a top-secret conference hosted by Winston Churchill and assigned to the navy’s investigation branch. There he used his specialist knowledge to help uncover the technical sophistication of Germany’s mines and torpedoes. In this memoir, originally published in 1961, he recalls how it became a dangerous, hands-on role, and how failure to disarm the weapons could have cost England the war.