The design of the Type XXI U-boat was a radical step in the history of submarine development; indeed, the vessel could be said to have been the prototype of the modern conventionally powered submarine. After the disastrous losses among conventional submarines during the early months of 1943, the German authorities concluded that the older boats, Types VII, IXC and IXD, were no match for Allied ASW techniques. The Type XXI design was the response to the deteriorating situation and the first boats were launched in the spring of 1944 only nine months after the initial presentation of the designs. These remarkable vessels incorporated a number of bold innovations including the schnorkel, which allowed it to run fast underwater employing its diesel machinery, and automatic torpedo reloading systems; and never before had such large and complex warships been built using standardised, prefabricated sections. The type was a new and menacing weapon which might have had a profound effect on the conduct of the war had it been introduced earlier. The 'Anatomy of the Ship' series aims to provide the finest documentation of individual ships and ship types ever published. What makes the series unique is a complete set of superbly executed line drawings, both the conventional type of plan as well as explanatory views, with fully descriptive keys. These are supported by technical details and a record of the ship's service history.