VESSELS MOORED IN HARBOR: NINE BATTLESHIPS; THREE CLASS-B CRUISERS; THREE SEAPLANE TENDERS; SEVENTEEN DESTROYERS. ENTERING HARBOR ARE FOUR CLASS-B CRUISERS; THREE DESTROYERS. ALL AIRCRAFT CARRIERS AND HEAVY CRUISERS HAVE DEPARTED HARBOR. No INDICATION OF ANY CHANGES IN U.S. FLEET.
"ENTERPRISE" AND "LEXINGTON" HAVE SAILED FROM PEARL HARBOR.
In his office at the Japanese consulate in Honolulu on the night of Dec. 6, 1941, Vice Consul Morimura, 27, glanced at this message, buzzed for his code clerk, ordered the report sent to Tokyo and shortly went off to bed. At 0120 hours the next morning. Vice Admiral Chuichi Nagumo, commander of a Japanese task force, received the relayed message from Tokyo. It was the last word required by
Nagumo before mounting the Japanese attack on Pearl Harbor. Vice Consul Morimura had done his job well.
Swimming Spy. The vice consul was not a diplomat, and his name was not really Morimura. He was Takeo Yoshikawa, former ensign in the Japanese Imperial Navy, who had been sent to Honolulu in April 1941 on espionage duty. Now, 19 years after Pearl Harbor, writing in the authoritative United States Naval Institute Proceedings, Yoshikawa details his role as Japan's eyes and ears in the days before Pearl Harbor.
Yoshikawa trained for his job for four years, studying everything on the U.S. Navy that he could get his hands on: Jane's Fighting Ships, U.S. books, brochures, newspapers, magazines (including United States Naval Institute Proceedings). Arriving in Honolulu, he set up his one-man operation. "I habitually rented aircraft at the John Rodgers airport in
Honolulu for my surveillance of the military air fields, and walked nearly every day through Pearl City where I could readily survey the airstrip on Ford Island and battleship row in Pearl Harbor." It was all quite simple: "I made many observations on underwater obstructions, tides, beach gradients, and so forth, while on swimming expeditions."
Yoshikawa never dared to seek an accomplice among the local Japanese, who, he felt, were distressingly loyal to the U.S. "However, with all of my various sources of information, plus the local newspapers and radio ... I was able to send a constant series of messages to Tokyo." In that stream was included information about the number and type of ships at Pearl Harbor, local defenses, location of fuel dumps, disposition of ships. He noted, among many other things, that U.S. battleships were often moored in pairs; this indicated that torpedo attacks against the inboard ships would be ineffectual. That report, he says, "caused a strong emphasis on dive-bombing with specially built bombs evolved from 16-in. armor-piercing shells."