The immediate events leading up to the epic attack on the U.S. fleet at Pearl Harbor began in January 1941 when Admiral Isoroku Yamamoto, supreme commander of Japan's war fleets, sent a letter to Japan's war minister. Yamamoto expressed the opinion that Japan could not hope to attain its goal of expansion in the Far East unless it eliminated the considerable influence of the United States in that region. And the surest and most effective way to remove that influence would be a surprise attack on the U.S. Pacific fleet.

Air ace Minoru Genda agreed with this view. Furthermore, he was convinced that airpower would be more effective than battleships in the assault on Hawaii. Genda soon found himself in charge of planning the operation and training the flight crews, endeavors that continued well into November.

Meanwhile, although the Japanese operation was top...