Americans - Bombe

East Coast

During 1942, the United States had to deal with German U-boats off of its east coast. German cryptanalysts were able to read Allied Naval communications and silhouettes of ships were distinct to the Germans during the night, so there wasn't any letting up for passing ships. Furthermore, the Allies could not break the German's enhanced 4-rotor Enigma encoded messages.

Confidentiality

The English were skeptical about the Americans ability of keeping their cryptanalysis work a secret. In the spring of 1942, the U.S. Navy worked with the National Cash Register Company, NCR, located in Dayton, Ohio, to build cryptanalytic machines. Joseph Desch an engineer at NCR, headed the project and swore to complete secrecy. Around this time, the U.S. and Great Britain slowly but surely began working together to try to find a solution to combat the 4-rotor Enigma. Because the U.S. had a lot more resources than England, they were able to expand their research into purely electronic designs.

OP-20-G

OP-20-G was the U.S. Navy's cryptanalysis department. After collaborating back and forth, the U.S. was given the go-ahead to build a more efficient Bombe for the 4-rotor Enigma, under deputy chief Commander Wenger. Some members of the GC&CS went to Washington, D.C., to visit the OP-20-G and draw up formal arrangements for responsibilities. The U.S. headed the Pacific Theater and Great Britain headed the European and Atlantic area. However, both sides ended up doing work on the other side as well.

Breakthrough & Sacrifice

Towards the end of 1942, the English managed to seize cryptographic materials and documents from U-boat U-559. In the vicinity of Port Said in the Mediterranean Sea, the HMS Petard intensely depth-charged the sub causing it to surface. Right after the the U-boat crew abandoned ship, members of the Petard boarded U-559. Officer Anthony Fasson and Seaman Colin Grazier was desperately handing off vital equipment and documents to another Royal Navy man, Tommy Brown because the submarine was taking on water very quickly. As Fasson and Colin had the last piece of equipment hoisted up to Brown through the conning tower the sub sank and Fasson and Colin did not make it out on time. Brown and other members jumped off the sub and saved their lives. However, Fasson and Colin did not die in vain. Now, Bletchley Park was able to read messages with a day and a half to 10 day delay tops. This once again began helping Allied convoys. Nevertheless, the U.S. Navy began to build a stronger Bombe at the NCR.

Battle of the Atlantic

The U.S. began bringing the fight to the German wolf packs in the Atlantic in May of 1943. The U-boat fleet suffered a severe loss, so much so that caused German Admiral Doenitz to withdraw from the western and middle Atlantic. Despite this Allied success, Germany was still sinking ships and thus the need to break their encoded messages was still evident.

U.S. Success

After many working shifts at the NCR, the U.S. was finally able to read German 4-rotor Enigma enciphered messages with their newly created Bombes. During the summer of 1943, the U.S. sank multiple refueling U-tankers thus not allowing the U-boats to roam as far and as much as they normally did. The Bombes were quickly ordered to be moved from Dayton to Washington, D.C. at the Naval Communications Annex, to increase their effectiveness. During the entire war the U.S. captured or sunk 95 U-boats.