The first of two volumes covering the career histories of all of the U-boats which saw action in World War II. The histories of some 1200 vessels are covered and each entry aims to be easily accessible. Every aspect of a boat's activities are covered, from laying the keel to its ultimate fate. Each entry gives locations and dates of units and any boats served with, commanders, number of patrols undertaken, ships sunk along with names of vessels and locations, incidents of note, re-fuelling by U-tankers and supply ships, attacks on shipping, survivors picked up and finally the ultimate fate. Appendices allow cross-referencing and contain such material as Deutsches Feldpost Numbers.