Any story about the On-The-Roof Gang has to start with Chief Radioman Harry Kidder. Known as the “Pappy” of the group, Chief Kidder held an esteemed place of honor in the opinions of those who he formally and informally instructed in Radio Intelligence operations. Many stories circulated about the Radio Intelligence skills of Chief Kidder. It is difficult, however, to confirm most of these stories as true – his legend is as strong as his skill was!

What is known about Chief Kidder is that he was an amateur radio enthusiast and an expert Morse operator stationed in the Philippines in the 1920’s. While practicing his hobby and profession, he noticed strong telegraphic code signals he did not understand. Because of the prevalence of the Imperial Japanese Navy (IJN) in the Pacific, and the 1923 CNO request to monitor Japanese communications, he taught himself the Japanese alphabet, Kata Kana, and the equivalent telegraphic code. He copied the IJN transmissions and passed the intercept logs to his commanders, who saw the value in these activities.

When the need was identified for official Radio Intelligence training by Navy Headquarters in Washington, DC, Lieutenant Laurance Safford, the father of naval cryptology, brought Kidder to Washington, DC to teach his skills to other carefully-selected Radiomen. Kidder designed and helped build the concrete schoolhouse on the roof of the Main Navy Building and taught the first three classes, where his legend grew.

In the years leading up to World War II, it is fair to say that no other Radio Intelligence operator had a greater impact on the ability of the U.S. Navy to intercept and exploit IJN tactical communications.

It has been said that Chief Kidder “laid the cornerstone” of the On-The-Roof Gang and while he may not have a household name, his legacy lives on in the US Fleet Cyber Command, U.S. Tenth Fleet, and in the Cryptologic Technicians of today’s Navy.
There is much more to come about Chief Kidder.