Between the two wars, Hogan put his engineering training to work in the private sector, when he joined Warner Brothers Theaters in Philadelphia as a sound engineer. This career would span over 30 years and include work on the movie “Ben Hur.” He was an active naval reservist participating in yearly summer cruises, training, and related activities.

Just when and how he came to the attention of future Rear Adm. Joseph Wenger is unknown, but an OP-20-G document had him reporting for active duty on Dec 8, 1941 at the Main Navy building on Constitution Ave, Washington DC. “On 1 January 1941, the present Section was in operation as a part of Section OP-20-GY.  The operating personnel consisted of two permanently assigned Civil Service employees who were former Navy Chief Petty Officers, and seven Reserve Petty Officers… A former Chief Radioman (Pete Deffert) was given a Civil Service appointment and placed in charge of the machine room. This supervisor was directly responsible for all machine procedures and formulated and directed all machine work….”

Cmdr Hogan (right) with Cmdr Ralph Hayes (OP-20-G Training and Personnel Officer) outside the Hogan home in
Alexandria, VA, circa 1942. Source: Harold O. Hogan Collection

In 1938, (then) Lt. Wenger proposed a mass method for decoding messages which was later adopted and used extensively during World War II at Washington, Pearl Harbor and Melbourne. This method used standard IBM equipment (including IBM 405 Alphabetical Accounting Machines, IBM’s flagship product of the era) when available including punch, sorter, reproducer, collator, and tabulator.

In any event, Hogan would become the sixth OIC of the IBM Machine section (OP-20-GS). Wenger had set up the unit in 1931-1932. Thomas Dyer, Wesley Wright, Jack Holtwick, and Pete Deffert would each take turns at the helm of the machine section of OP-20-G in the years prior to the war. At the time they were quietly the “who’s who” in the use of machine technology in naval cryptology. “Tommy” Dyer would later be known as the “Father of US Navy Machine Cryptanalysis.” In 1932, Dyer became the first machine operator in the US Navy cryptologic organization. 

From what can be determined, Naval Reservist Harold O. Hogan joined the unit in Washington shortly after Dec 7, 1941 succeeding Lt. Deffert as officer in charge of the section, although Deffert remained with the unit. Lt. Hogan had been one of 29 reserve officers recommended to be mobilized to the office of Director of Naval Communications in June 1940. On June 15, 1942, “Lt. Hogan received temporary promotion to Lt. Cmdr. USNR,” according to the 1942 War Diary for the GS section. Hogan was from the Fourth Naval District headquartered in Philadelphia. This group of reserve officers, including Howard (“the brain”) Engstrom, Ralph Hayes, Prescott Currier, W.F. Harrington, and Griffith Chiles, would be the core group of reserve officers that would serve with the OP-20-G organization. “Many of these officers served on active duty from before the outbreak of World War II until after war’s end, some transferred to the regular Navy; all who served contributed to some degree to the organization’s wartime and postwar success.” In June 1941 all fleet reservists were recalled to active duty. Consequently, the Civil Service personnel in the machine room were given an extended leave of absence and reported as Navy personnel.

In June 1943, Cmdr Hogan appeared in a photo taken with his fellow communications officers “on station” during the Battle of Coral Sea and the Battle of Midway. Included in this group were Rudy Fabian (FRUMEL), Lee Parke, Jeff Dennis, Howard Engstrom, Rosie Mason, Earl Stone and E.S.L. “Sid” Goodwin (FRUMEL). The photo was taken in front of the chapel at the Naval Annex on Nebraska Avenue. The late Captain George P. McGinnis described this group as the “powerhouse of naval communications” during the early days of WWII. Source: NCVA

In early 1942, the Navy communications brass thought, while existing IBM business technology was good, it did not always meet the specific needs of the US Navy and codebreaking. Captain Jack Redman CO of OP-20-G, who considered himself a personal friend of the legendary Tom Watson of IBM, approached Watson about a meeting to discuss IBM developing a new series of specific machines for the Navy. Watson agreed to a meeting to be held at OP-20-G at Main Navy. On the appointed date Watson was a no show!  Instead, Watson sent a single IBM representative who asked a lot of questions and made notes in his IBM “think pad” as the company called their paper notebooks in those days. It happened so fast, no one at OP-20-G got the man’s name or knew who he was.

Thus was born the NC-1 machine, the first of a series designed specifically for Naval Communications organization, hence the designation NC for these machines. According to Louis Holland, “The NC-1 through NC-5 equipment were developed and placed in use by the mid to late 1942….” I have searched the OP-20-G correspondence files as well as all the files in the National Archives and have to-date, failed to locate any correspondence bearing upon the subject of the NC machines. The only exchanges between the IBM Corporation and the NC machines appears to have been verbal! Perhaps this accounts for the almost unbelievable speed which these machines were conceived, built and put into operation. IBM would only charge the Navy one percent above the actual cost to develop and manufacture these machines as it was IBM’s policy for all war-work. According to Holland, OP-20-G was their largest account in Washington during the latter years of the war.

NC-4 Tabulator — known as “the work horse tabulator” of the Pacific War was designed specifically by IBM for the US Navy codebreaking process. (Holland). Source: NCVA

Holland was OP-20-G and NSA data processing veteran, hired as a civilian Special Assistant for Automatic Data Processing by the Naval Security Group Command in 1965. There he would write a classified report tracing the development of machine processing including the NC machines within the NSG.

By that time, OP-20-G was predominately processing Japanese Navy problems, although Howard Engstrom would run a separate section addressing German codes. A number of the NC machines would prove commercially viable after the war. Many business and governmental entities began employing IBM tabulating and sorter machines during the 1930’s, so their use was no secret. Even insurance companies in Tokyo were using IBM tabulators in the 1930’s. So the Japanese had some access to these IBM machines but either did not think to utilize them for codebreaking or chose not to. Nor did Japanese naval planners and radio experts seem to have a clue that the Americans may be utilizing this technology and either ignored or were not aware of some of the obvious clues that the Americans were using this technology. It was one of the best kept secrets of World War II.


Photo (right): Officers with OP-20-G gather for a formal wartime photo in front of the chapel at the Naval Annex on Nebraska Avenue in Washington DC. Source: Harold O. Hogan Collection

The JN-25 code was the most prominent, as the OP-20-GS war diaries written by Hogan attest. Hogan’s section worked on these on war codes thru the Battle of the Coral Sea and the Battle of Midway and would help physically move the section to Nebraska Avenue in 1943. On 25 May 1944 a detailed technical report labeled TOP SECRET was prepared by Lt. Commander H.O. Hogan’s GS section for Frederic Freeborn on the IBM processes at OP-20-G. Freeborn was the IBM boss at GCCS and Bletchley. It appears to have been prepared for a presumed meeting with Commander W.A. “Ham” Wright, USN. The report indicated that only a few GS repair mechanics had worked for IBM, however, a number of people had previous experience with IBM while working for commercial firms. The report went on to include the special collaboration with IBM on the NC-4 and other specialized machines. This report indicated as of May 1944 JN-25 was still the primary that the group was attacking. It also indicated how the units in Melbourne and Hawaii were integrated into the overall process. The meeting/report is an example of the British/American co-operation and information-sharing just weeks before the D-Day invasion.

Compiled by Jim Schlueter and Deb Hogan Smith