This timeline has been long neglected but I’ve recently begun to add to it. I’ve indicated my variety of sources. Military information is primarily from the wikipedia timeline. Over the years I’ve found other excellent timelines online regarding the history of cryptography or WW2. These included the NSA Cryptologic History Timeline and the WW2 Database.

Date Military/U-boats Cryptologic Dayton
1860   first US patent for cryptographic device granted  
18??     John Patterson founds the National Cash Register Company
1914 At the start of World War I, Germany had 48 submarines of 13 classes in service or under construction; in their initial campaign in the North Atlantic, German U-boats had sunk nine warships while losing five of their own number    
24 January 1918   Arthur Scherbius received a patent for a cipher machine now known as the ENIGMA  
1919 Part V of the 1919 Treaty of Versailles had imposed severe restrictions on the size and capacities on the armed forces of the Reich. In regards to the Navy, Germany was allowed no submarines, no naval aviation, and no battleships Hugo Koch, a Dutchman, comes up with the idea for the Enigma cipher machine; Damm receives Swedish patent for cryptoraphic device using “rotor” (Deavors, p. 5_)  
1921   William Friedman goes to work for the Army Signal Corps  
1923   Arthur Scherbius produces an Enigma machine for the commercial market  
January, 1924   Lt. Laurence Safford takes the head of the Reseach Desk at the US Navy Codes and Signal Section (later became Op-20-G)  
1925   First US Navy radio intercept station set up on Guam followed by two in the Philippines and one in Shanghai  
9 February 1926   German Navy introduced the ENIGMA machine as “Radio Key C” for communications security  
July, 1928   The “On the Roof Gang” begins training on the roof of the old Navy Department.  
Date MilItary Cryptologic Dayton
April, 1930   William Friedman authorized to hire three junior cryptanalysts to begin a bureau known as the Signal Intelligence Service  
1931   Japanese cryptographers begin use of an “unbreakable” cipher called “Red” produced by a machine using rotors with a complex wiring arrangement  
1932   In Poland, Marian Rejewski recovers wiring of Geman military Enigma rotors  
1 October 1933 Unterseebootsabwehrschule (U-boat war school) founded.    
11 March 1935   Navy cryptologic organization redesignated as Op-20-G  
29 June 1935 The Anglo-German Naval Agreement (A.G.N.A) of June 18, 1935 was a bilateral agreement between the United Kingdom and German Reich regulating the size of the Kriegsmarine in relation to the Royal Navy; the launch of U-1    
27 September 1935 Unterseebootsflotille Weddigen commissioned by its first chief, Fregattenkapitän Karl Dönitz    
1936   Red system broken by US Navy  
1 January 1936 The appointment of Kapitän zur See Karl Dönitz to the post of Führer der Unterseeboote    
1937   Introduction of the Purple Japanese cipher machine  
April 1938     Harry Williams, at the request of Col. Edward A. Deeds, President of the National Cash Register Company, hired Joseph R. Desch to begin NCR’s Electrical Research Laboratory
15 March 1939 Germany invades Czechoslovakia    
1 June 1939   The Japanese naval code JN-25 introduced  
1 September 1939 Germany invades Poland    
3 September 1939 France and Britain declare war    
Date MilItary Cryptologic Dayton
1940   By the summer of 1940, through the collaboration of the staff of William Friedman of the SIS and Lt Safford Japanese diplomatic traffic was easily read  
14 March 1940   First bombe operational at Bletchley Park  
Summer 1940 Battle of Britain    
September 1940   Japanese Purple cipher broken by US Army; first JN-25 decrypts by Op-20-G  
October 2 1940     Joseph Desch writes in December to Dr. George Harrison of the NDRC that on October 2nd his laboratory staff–Mr. Robert Mumma and Mr. Louis DeRosa–are beginning work on the development of high speed electronic counters.
23 January 1941   Intelligence chiefs of US Army and Navy established list of eligible readers of “Magic” Intercept  
March 1941     The National Defense Research Committe appoints Joseph Desch an “Official Investigator” and requires him to sign the first of a series of pledges of secrecy
9 May 1941 U-110 captured intact by the British (Williamson, Wolf Pack)    
June 1941   Joseph Rochefort takes command of the radio intelligence unit of the 14th Naval District in Hawaii, renaming it the Combat Intelligence Unit  
October 1941     Desch’s lab develops a counting bank, using his thyratron tubes, capable of counting at 1,000,000 impulses per second (1 MH in today’s terms). Desch presents a talk on this topic in December at an Electronic Counter Conference in Washington. George Harrison of the Instruments Section of the NDRD later write Desch that his talk was “quite effective”.(NCR Archive)
15 November 1941 Launch of U-459, the first Type XIV tanker U-boat, or so-called Milchkuh (Williamson, Wolf Pack)    
Date MilItary Cryptologic Dayton
13 January 1942 Operation Paukenschlag offensive against shipping off the American coast begins. The start of the second “Happy Time” (Williamson, Wolf Pack)    
1 February 1942   German Navy introduced 4-rotor ENIGMA for U-Boats  
FRUMEL, US Navy’s Fleet Radio Unit, Melbourne, established to assist General MacArthur, 1942      
11 February 1942 The Scharnhorst and Gneisenau and Prinz Eugen rush out of Brest through the English Channel to northern ports, including Wilhelmshaven, Germany; the British naval units fail to sink any of them.    
5 March 1942   Station HYPO began reading Japanese system JN-25  
March 1942     US Navy and National Cash Register Company sign a contract to develop and construct specialized machines. This contract establishes the Naval Computing Machine Laboratory
5 May 1942 The Battle of the Coral Sea begins, set up by Station HYPO COMINT    
June 1942   More than 600,000 tons of shipping were sunk (Budiansky, Battle of Wits, p. 236). This was close to Admiral Doenitz’s goal of 700,000 which he felt would cripple Britain  
18 June 1942 Manhattan Project begins; Churchill arrives in Washington for meetings with Roosevelt    
30 July 1942 WAVES (Women Accepted for Voluntary Emergency Service) established    
4 September 1942     US Navy approves the plan for bombe construction
December 1942   The total figures of Allied losses during 1942 in the Atlantic: 1,664 ships, of 7,790,691 tons. U-boats alone sank 1,160 ships and 6,226,215 tons.(Parrish, The Ultra Americans)  
Date MilItary Cryptologic Dayton
14 January 1943 Casablanca Conference of Allied leaders begins. Churchill and Roosevelt discuss the eventual invasion of mainland Europe, the invasion of Sicily and Italy, and the principle of unconditional surrender    
1 February 1943   SIS began Project Venona  
7 February 1943   U.S. Navy OP-20-G moved to Nebraska Avenue  
17 March 1943         President Roosevelt orders that that Navy Contract NXs 7892 with the National Cash Register Company is given the highest possible preference rating (AAA) commencing this date.
April 1943     WAVES begin arriving by train at Union Station in Dayton to report for duty at the US NCML.
2 May 1943     First two US Navy bombes at the USNCML begin tests (Budiansky, p. 343)
June 1943     There were some 65 officers and 500 enlisted personnel stationed at the USNCML for training purposes.
31 August 1943   first US Navy bombes arrive in Washington (Budiansky, p. 344)  
1 September 1943   First Bombe shipped to Nebraska Avenue  
14 January 1944 BRUSA Agreement — US/UK COMINT relationships during World War II    
4 June 1944   U-505, with a wealth of cryptographic material and machines intact, became first enemy warship captured by an American naval boarding party since the War of 1812  
30 January 1945     The speed and efficiency with which those projects were processed is indicated in a letter of 30 January 1945 from DNC to DinC, USNCML stating in part30 Jan “The skillful and expeditious handling of a special project for the Asst DNC, Op-20-G, during the months of December 1944 is an outstanding example of magnificent accomplishment and a most important contribution to the war effort.”
15 August 1945 Japan announced its surrender    
15 Aug 1946     A continuation of the Research and Development work at Dayton was covered by a final contract dated 1 July 1945 and terminated 15 August 1946.
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  • Inside You’ll Find…

    WHO worked during the war? Find the Personnel section. Also, Joseph R. Desch
    WHAT were their goals? By the Numbers. Also, The US Bombe
    WHY? History of the Bombe Project A contemporary account of the reasons and the plans for their project for the Director of Naval Communications, 1944.
    WHERE was the project: In Dayton, it was in Building 26. In Washington, it was housed at the Naval Communications Annex