Three U.S. Navy top-secret cables instructing its Third Fleet commander not to go near Nagasaki or Hiroshima days before the atomic bombings of those cities 73 years ago have been found at the U.S. National Archives by a Japanese researcher, the Mainichi Shimbun has learned.
The cables were sent between Aug. 1 and 4 in 1945 from Pacific Fleet Cmdr. Chester Nimitz to Third Fleet Cmdr. William Halsey who was leading Task Force 38 comprising aircraft carriers among other vessels.
The documents were found last year by Yozo Kudo, the director general of a civic group in the western Japan city of Shunan in Yamaguchi Prefecture researching American records to figure out the extent of damage caused by U.S. air raids during World War II.
According to Kudo, the cables appear to be the first confirmation that a U.S. Navy fleet on the frontline received information about the atomic bombings before they happened.
Task Force 38 was scheduled to attack the city of Sasebo in Nagasaki Prefecture where the Japanese Imperial Navy had a major base, on Aug. 5, 1945. The flotilla, while still in the Pacific, received a cable dated Aug. 1 that said one of the targets of attacks planned on Aug. 4 was changed from the ancient capital city of Kyoto in western Japan to Nagasaki.
Then the second cable dated Aug. 2 informed the Third Fleet commander and the task force that a "special operation" will be conducted on Aug. 4 or 5 at a time to be announced later. The cable then instructed, "No ship or aircraft of the Pacific Fleet will come within 50 miles of Nagasaki, Kokura or Hiroshima from four hours before to six hours after the announced time." Kokura in the Fukuoka Prefecture city of Kitakyushu was one of the planned targets of the atomic bombings.
According to Kudo, bombers sprayed aluminum chaff to confuse enemy radars, but those thin metal fragments increased the risk of an atomic bomb detonating at an altitude higher than planned. The reasons behind designating the time of no entry were to make sure that the "special operation" would go smoothly and to avoid American service members' exposure to radiation.
The third cable dated Aug. 4 ordered "no interference with operations of the 509 Bomb Group," which apparently meant the 509 Composite Group of the U.S. Army that carried out the atomic bombings of Hiroshima and Nagasaki. Nimitz further wrote, "You send no planes over Kyushu or western Honshu until specifically authorized by me. It is my intention to give you freedom of action as soon as the special mission has been completed. At this time it appears probable that task will be completed on the 5th" of August.
Kyushu is the main island in southern Japan where Nagasaki is located in its north; Honshu is the main island in the Japanese archipelago and Hiroshima is situated in its western portion.
After the cable, Task Force 38 headed toward Tohoku and air-raided military facilities in the northern Japanese prefectures of Miyagi, Iwate and Yamagata on Aug. 9 and 10. It appears that the atomic bombings were behind this change of target by the task force.
Kudo published his analysis of the cables in July in a book about air raids on Japan by aircraft based on American aircraft carriers.
Professor Haruo Tomatsu of the National Defense Academy of Japan, who specializes in diplomatic history, commented that the cables indicate that the United States government, which was preparing the atomic bombings as top secret operations, saw the necessity to inform the top brass of the navy fleet operating near Japan of the operations days before they were carried out, out of consideration for the bombings' impact on their sailors and airmen.
(Japanese original by Ken Yamada, Osaki Regional Bureau)