The Kriegsmarine’s submarines, the U-boats, proved to be the most effective and deadly arm of the German navy in World War II. Built to harass Allied shipping, the U-boat “Wolfpacks” almost succeeded in bringing Britain to her knees in their campaign to restrict supplies from crossing the Atlantic. By 1942, their most successful year, U-boats had sunk 1,664 vessels – a massive 7.26 million tons of shipping. However, by mid 1943, with the development of improved radar and antisubmarine aircraft in both Britain and the United States, the tide had started to turn. This is a comprehensive guide to the submarine arm of the German navy in World War II. -- From the book jacket.

Combat flotillas -- Training flotillas.