Books about German U-Boats.

U-Boats were military submarines operated by Germany, particularly in World War I and World War II. Although in theory U-boats could have been useful fleet weapons against enemy naval warships, in practice they were most effectively used in an economic warfare role (commerce raiding), enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada, the British Empire and the United States to the islands of Great Britain. Austrian submarines of World War I were also known as U-boats.