The incredible story of how HMS Petard and her gallant crew seized priceless German Enigma codebook from a sinking U-boat is one of the greatest stories of World War II. An attack by a British destroyer on a German U-boat in the Eastern Mediterranean in October 1942 altered the course of the entire war. The capture of secret coding material from U-559, at the cost of two of HMS Petard's crew, enabled Bletchley Park's codebreakers to successfully crack the U-boat cypher.