machines.' (43) The U-boat problem fell exclusively to the United States Navy.(44)

By the spring of 1944, ninety-six operational Bombes routinely broke the U-boat messages. The average delay in breaking the daily key settings was only twelve hours. As a result, the Navy could read all the Atlantic U-boat messages sent in the latter half of the day at the same time as the Germans. 'In fact, during these hours the translation of every message sent by a U-boat is at hand about twenty minutes after it was originally transmitted.' (45)

Once the Bombes retrieved the daily U-boat keys, the machines were then set to search for non-naval settings. So many messages came out of Europe that even Britain's highly effective three-rotor Bombes couldn't keep up. Approximately 55 percent of the operational time on an American Bombe was dedicated to naval keys, the remaining 45 percent on non-naval, under the direction of theBritish.(46)

To further improve the system, the British requested that the U.S. Navy manufacture fifty additional four-rotor Bombes. Their request was more to further the work done on German Army and Air Force messages than to increase the efficiency of the German naval problem. However, in early September 1944 NCR had completed only twenty-five Bombes, and the Navy determined that 'Current rapid developments in the prosecution of the war have made it unnecessary to complete the remainder of the fifty (50) additional Bombes.' (47)

Certainly, one of the developments that aided in the 'prosecution of the war' was the advance knowledge of U-boat locations and activities. Because of the information learned from Enigma messages, the Navy's ability to destroy the submarines increased significantly. By the end of the war, the United States sank or captured ninety-five German U-boats.