My late father served in the Navy in the Pacific during WW II.
From America’s 1st Freedom: https://www.americas1stfreedom.org/articles/2016/12/7/american-warrior-pearl-harbor-75-years-ago-today/
by Frank Winn, Guns & Gear Editor
Wednesday, December 7, 2016
Partly cloudy skies greeted the residents of Oahu as they rose on Dec. 7, 1941, on what might otherwise have been another idyllic tropical Sunday. As the sun edged up out of the blue Pacific, it seems profoundly unlikely that any knew the scale of disaster that was winging its way from 230 miles north of the island.
Except, perhaps, for Takeo Yoshikawa.
Since April 1941, the former Imperial Japanese naval officer had been spying extensively on military installations around the island. Operating under a relatively weak “cover” identity as Tadashi Morimura, he lived on the grounds of the Japanese Consulate with a mission to simply observe the comings and goings of the Pacific Fleet at nearby Pearl Harbor. His good English, memorization of the outlines of U.S. Naval vessels and study of published U.S. Navy doctrine prepared him well for his clandestine observations.
Before long, his detailed communiqués on ship movements were flowing back to superiors in Japan. Despite traveling over “open” (commercial) radio channels and in a code already broken by Navy cryptographers, he would manage to lay the crucial groundwork for the devastating attack without arousing any suspicion. Yoshikawa doubtless did not know the actual date for the attack, and was arrested with other Consular staff the morning of the raid. He was repatriated to Japan in August 1942 under suspicion as to his role.
Yoshikawa/Morimura’s espionage remained undiscovered for many years after World War II, but the damage for which he helped set the stage was immediately and indelibly impressed on generations of Americans before the day was out.
The scale of Admiral Chuichi Nagumo’s assault force may be a difficult to appreciate. The Imperial Japanese Navy sent 60 percent of its aircraft carrier force (the largest and best-equipped in the world by a good margin at the time)—a total of six “flat tops”—toward Oahu’s military installations. Even by today’s standards, this would constitute the second-largest carrier contingent afloat, and the aircraft the twelfth-largest combined air force (414 aircraft, of which 353 would actually be launched at U.S. installations) in the world. Two battleships, three cruisers, nine destroyers, 27 submarines (four “midget”) and eight tankers escorted the carriers to their attack position.
Two waves hit U.S. installations, the first arriving at 7:48 a.m. In a happy coincidence that would go on to affect the entire course of the Pacific war, the three American aircraft carriers—sister ships Lexington and Saratoga as well as Enterprise—were not in Pearl Harbor on the morning of the seventh. Saratoga was in San Diego, and the “Lady Lex” and “The Grey Ghost,” though in Hawaiian waters, were on exercises with their cruiser escorts. The IJN aerial armada was thus deprived of their top two priorities.