This is the memoir of one of the most respected codebreakers of World War II. After graduating from the Naval Academy in 1924, Dyer served in the battleship New Mexico (BB-40). During this duty his talent at puzzle-solving came to the attention of communications experts. He was stationed in Pearl Harbor from 1936 to 1945 as head of the Navy's cryptanalytic unit. In an engaging style, Dyer discusses the successes of the unit, including their ability to provide intelligence to the fleet prior to the Battle of Midway. Alas, the communications intelligence community was divided by a good many jealousies, which Dyer discusses candidly, including the relegation of respected analyst Joseph Rochefort to jobs which did not take advantage of his talents. Captain Dyer was one of the first to use an IBM tabulator in his work, and has been called the "father of machine cryptanalysis." After the war he worked at the National Security Agency until his retirement in 1955. Dyer's memoir is particularly valuable for its behind-the-scenes look at the work of a group of men who were unsung heroes of the Pacific War but were long denied appropriate credit because of security restrictions.