Joseph R. Desch

Joseph R. Desch

1907 – 1987

Headed successful U.S. effort to break German U-boat Enigma code

Enshrined:  2008

Major Field of Study:  Electrical Engineering

Home Town:  Dayton, Ohio

Youth Activities:  At age 11, inspired by a crystal radio set he saw in in a store, taught himself electronics and built his first radio

High School:  University of Dayton Preparatory High School

Bachelor’s DegreeUniversity of Dayton, Bachelor of Science, Electrical Engineering, 1929

Engineering and Science Achievements:

Joseph Desch was hired at the National Cash Register (NCR) Company of Dayton, Ohio, in 1938 to begin an Electrical Research Laboratory. He was charged to investigate ways to incorporate electronics into NCR’s business machines.  By 1940 he and colleague Robert Mumma had designed and built a successful calculating machine using tube technology. By 1941 they had developed counters capable of a reliable top speed of 1.5 million counts of impulses per second.

Beginning in late 1942, working with the U.S. Navy, Desch and his team led a project of the highest priority and secrecy to crack the secret communications of the Nazi U-boats.  This crucial effort was mandated by the terrible toll the U-boats were taking on Allied shipping operations to supply Great Britain with vital provisions and materiel.  During 1942 alone, Nazi submarines sank over 1,000 allied merchant ships in the North Atlantic in what is known as the “Battle of the Atlantic.” This large loss was, in part, due to the difficulty of anticipating the U-boat attacks, a capability that could be enhanced if the Allies were able improve their ability to interpret encrypted message traffic to and from the U-boats.

For its submarine communications, the German Navy used a machine called Enigma, which encrypted text through letter substitution, or ciphers.

The Enigma used a complex method based on wheels or rotors, which resulted in about 3 X 10114 (10 followed by 113 zeroes!) ciphering possibilities.  Desch designed and built machines called “Bombes” to reverse the enciphering.  The Bombes incorporated Desch’s electronics to enhance speed, reliability and flexibility.  When analyzing a particular intercepted encrypted message, the Bombe determined the various settings of the Enigma at the time of message transmission, thereby enabling decrypting of the message with a captured Enigma or a locally-manufactured analog configured at the settings ascertained by the Bombe. 

The first Bombe had been developed by Polish cytologists prior to the war.  But in 1939, with the German invasion of Poland looming, the Poles shared their information with the British.  This enabled British intelligence, led by Alan Turing, to develop its own Bombe.  Armed with this capability, the British achieved a significant amount of success in decrypting messages encrypted by Enigmas that used three wheels.  The Nazis, however, introduced a four-wheel Enigma called “Shark” for U-boat traffic in February 1942, and it raised the potential number of ciphering possibilities to about 2 X 10145 (10 followed by 144 zeroes). This was more than the three-wheel British Bombes could handle, and because the US Navy was experiencing unacceptable losses to U-boats, it turned to NCR and Desch to develop an American Bombe that could successfully deal with Shark.

Desch’s project began in August 1942, and while progress was not as quick as originally hoped, his Bombe scored its first successful Shark cracking in June 1943.  From that point on, performance improved as more Bombes were produced and processing times to analyze German messages were reliably reduced to 20 minutes.

During one three-month stretch in mid-1944 after Desch’s Bombe had been put into wide use, the Allies were able to sink 76 percent of the operating German submarines.  The Bombes, by helping to pinpoint German U-boat locations, have been credited with about one-quarter of all U-boat sinkings from 1943 to the end of the war.  Meanwhile, the tide in the Battle of the Atlantic had turned, as the number of allied merchant ships lost to U-boats in the North Atlantic was reduced from over 1,000 in 1942 to 31 in 1944.

In total, during the war, over 200,000 items produced at NCR were shipped from Dayton to Washington DC, where the main decrypting operation was conducted.  Some 56 railroad carloads weighing 17 tons each were sent.

For his contribution, Desch was awarded the National Medal of Merit in 1947, but the project retained top secret status until 1995.

Additional Details:

Prior to hiring on with NCR, Desch pursued various occupations in the Dayton area, including:

  • Day-Fan Electric, supervising radio testing
  • General Motors Radios, also supervising radio testing
  • Free-lance inventor
  • Telecom Laboratories, conducting telecommunications research
  • Frigidaire Division of General Motors, working as a foreman in the process laboratory

After WWII, Desch continued his work with NCR until his retirement in 1972.  Notable accomplishment included co-patenting an electronic calculator with Mumma and working on development of the first completely solid state computer.

Desch was inducted to the National Security Agency Hall of Honor in 2011 and received the Stibitz Award from the American Computer and Robotics Museum in 2016.

The writer extends his thanks to Joseph Desch’s daughter, Ms. Deborah Anderson, for her assistance in composing this sketch.


Debrosse, Jim, and Burke, Colin, The Secret in Building 26, New York, Random House, 2004.

Lee, John A.N., Burke, Colin, and Anderson, Deborah, “The US Bombes, NCR, and 600 WAVES:  The First Reunion of the US Naval Computing Machine Laboratory,” Annals of the History of Computing, Spring 2000, retrieved 17 October 2016 from

“Joseph R. Desch,” Dayton Codebreakers, retrieved 17 October 2016 from

“Keeping the Secret:  The WAVES and NCR; Joseph Desch and the Bombe,” Dayton History Books Online, retrieved 17 October 2016 from http

Institute of Electrical and Electronics Engineers interview with Deborah Anderson, 1 July 2013, published in “Oral History:  Deborah Anderson,” Engineering and Technology History Wiki, retrieved 17 October 2016 from

Simpson, Ralph, “The History and Technology of the Enigma Cipher Machine,” Cipher Machines, retrieved 3 December 2016 from

“Battle of the Atlantic Statistics,” retrieved 4 December 2016 from

White, David Fairbank, Bitter Ocean, The Battle of the Atlantic, 1939 – 1945, Simon and Schuster, 2006.

Links:  Frequently updated.



Joseph Desch. Wikipedia.