THE U.S. NAVY'S ON-THE-ROOF GANG

A lightly fictionalized debut work focuses on pioneering codebreakers in the United States Navy in the years leading up to the Pearl Harbor attack.

Retired radio intelligence officer Zullo combines years of technical expertise with a passion for his subject to craft the first of two volumes about a group of 20th-century Navy cryptologists. Called the On-the-Roof Gang because classes were held on the roof of a Navy building, the effort involved 176 men trained between 1928 and 1941. The radio operators learned techniques of transmission analysis involving Japanese katakana telegraphic code in order to intercept Imperial Japanese navy communications. The key figure in the narrative is Petty Officer Harry Kidder, who in June 1924 is a Morse code expert and Navy radioman in the Philippines. An eager and enthusiastic ham radio amateur, Harry discovers puzzling extra letters in transmissions while pursuing his hobby. Determined to decipher what he has noticed, Harry finds out from a Navy memo that the letters are part of the Japanese katakana alphabet. He then asks a friend’s Japanese wife for assistance. She helps Harry develop a “symbol, sound, and letter chart.” Several months later, Harry, now back in the U.S., meets Lt. Laurance Safford, a radio communications officer in Washington, D.C., assigned to look into Harry’s claims. Alongside the two men is the brilliant Agnes Meyer, working as a civilian in Navy communications, who comes up with the idea to establish a training program, and the On-the-Roof Gang is born. The tale proceeds chronologically, discussing developments in code-breaking techniques during the 1930s as well as military history. Other chapters delve into Harry’s personal life and problems, including an incident in Hawaii that leads to his forced retirement before Safford works to fully reinstate him to the “Research Desk” in 1940.

The intriguing story picks up speed and tension toward the end, as Safford and Navy radio operators search for elusive “Winds Execute” messages that will provide evidence that shows what by then seems inevitable: “War with Japan was imminent and that the Japanese were likely to attack without warning.” While technically historical fiction due to the invented dialogue and scenes, Zullo’s book leans heavily toward nonfiction and will primarily appeal to readers interested in military history, code-breaking, and the war in the Pacific. The narrative sparkles with authenticity and is well organized and clear, enhanced by the judicious use of historical photographs and maps. But the inclusion of each of the 25 training classes tends to slow the dramatic pace. And while the fictional scenes are well crafted, Harry, Safford, and others remain primarily historical figures. Still, history buffs will appreciate the illuminating chronicle, which has been informed by archival sources, first-person accounts, and interviews with veterans. While some details could have been omitted to achieve a tighter story, the author’s firm grasp of events makes for a compelling read. Volume 2 promises to bring readers into the war. Kidder, affectionately known as Pappy, died in 1963 and was inducted into the National Security Agency’s Cryptologic Hall of Honor in 2019.

An engaging tale of some little-known Navy cryptology efforts before World War II.