The majority of the section's effort was directed towards Japan and included breaking the early Japanese "Blue" book fleet code.

This was made possible by intercept and High Frequency Direction Finder (HFDF) sites in the Pacific, Atlantic, and continental U.S., as well as a Japanese telegraphic code school for radio operators in Washington, D.C.

He worked out of Room 2646, on the top floor of the Navy Department building in Washington, D.C. Japan was of course a prime target for radio interception and cryptanalysis, but there was the problem of finding personnel who could speak Japanese.

By June 1940, OP-20-G included 147 officers, enlisted men, and civilians, linked into a network of radio listening posts as far-flung as the Army's.

This sounded like war, and although the message said nothing about any specific military action, Kramer also realized that the sun would be rising over the expanses of the central and western Pacific by that time.

Due to various constraints and bumblings, Short got the message many hours after the Japanese bombs had smashed the US Navy's fleet at anchor in Pearl Harbor.

In February 1942 power struggles within the Navy resulted in the sidelining of Laurance Safford, with the support of Admirals Ernest King and Richmond K. Turner (and Joseph Redman) for the centralizing of control of naval intercept and codebreaking in Washington.

Safford was shifted to an administrative support and cryptographic research role; thus was sidelined for the remainder of the war, as ultimately was Joseph Rochefort in Hawaii.

[3] With Japanese advances in the Philippines, a possible invasion of Hawaii, and greater demand for intelligence, OP-20-G undertook two courses of action: In Summer 1942 the Navy went through the motions of perhaps co-locating with the Army's SIS but Commander Joseph Wenger had picked out the "perfect new home" for the rapidly expanding OP-20-G and commandeered[5] a private girls' school Mount Vernon College for Women for $800,000 (a fraction of what the buildings and grounds were worth), in 1944, compensated $1.038 million.