In 1924, an American general filed a 324-page report predicting the exact target, day, hour, and method of the Japanese attack on Pearl Harbor. The War Department buried it. He was court-martialled and forced out of the army. Pearl Harbor happened seventeen years later. He had been dead for five.

His name was William Mitchell. Everyone called him Billy. He was a brigadier general, the founding father of American military aviation. In 1924 the army sent him on a tour of the United States's Pacific defences. He came back with a report.

He had been to Hawaii. He had been to the Philippines. He had been to Japan. He had watched the Imperial Navy launch torpedo planes from a carrier. He measured the wind, the time zones, and the angle of approach. In his report he wrote: "Attack will be launched as follows. Bombardment attack to be made on Ford Island at seven thirty a.m. Attack on Clark Field at ten thirty a.m." He named Pearl Harbor. He named Sunday morning. He named the carriers.

The War Department filed the report and ignored it. When Mitchell pressed for an independent air force and called the army and navy leadership's neglect of air power "almost treasonable", he was court-martialled, on the direct orders of President Calvin Coolidge, for insubordination. One of the thirteen judges was Douglas MacArthur, who called it the most distasteful order he ever received. Mitchell was convicted on the seventeenth of December, 1925, suspended for five years, and forced to resign. He died in February 1936, aged fifty-six.

Five years and nine months later, on Sunday the seventh of December, 1941, six Japanese aircraft carriers steamed to a point two hundred and thirty miles north of Oahu. At seven fifty-five a.m., three hundred and fifty-three Japanese aircraft attacked Ford Island, Pearl Harbor, and every American battleship in port. Two thousand four hundred and three Americans died. Nine hours later, three hundred Japanese aircraft attacked Clark Field in the Philippines. Mitchell had been twenty-five minutes off.

In 1946, Congress posthumously awarded him the Congressional Gold Medal for his foresight. In 2005, it commissioned him as a Major General. The court-martial transcript is still on file at the National Archives. They knew. Subscribe.