On a page of Travel Diary dated September 30, 2002, I reported that I was surprised by a note written by Mr. Masataka Chihaya, ex-Navy Commander who was an operation stuff of The Combined Fleets of Imperial Japanese Navy at the end of war. He wrote it right after the end of war. I was surprised to find from his note that the Japanese navy had no sense of intelligence at all. Hereafter, I would like to add a little more to it today.
In 1942, the Japanese navy aircraft carrier fleet not only failed to occupy the Wake island but lost all of its fleet at that time. It is admitted by everyone now that the results of this battle led Japan to the defeat of Pacific Wars. The following are the other causes of defeat which I heard directly from the persons concerned.
One of them is as follows: When the Japanese Navy were planning the attack on the Wake Island, they used "X" for the Wake Island as a secret language. A few day before the start of their operation, the Intelligence Department of Japanese Navy which was stationed at Hiyoshi, Kanagawa prefecture, caught an emergency message from the Wake Island. It was not coded telegram but in open English. It said "Purifying Machine was out of order. Send us drinking water immediately."The stuffs of the department were made of reserved officers who volunteered to join Navy from the university students. But a young regular officer who was graduated from the Navy Academy managed the Department. When he tried to transfer the enemy message to all Japanese attacking forces, Mr. "T", the senior of reserved officers, advised him not to do that because this message might be a trap. The young officer who had not even the beginners' knowledge about intelligence dared to send it. After the end of war, it was made clear that the U.S. Navy could confirm the Japanese target was the Wake Island and prepared the all-out anti-attack operation, and that they were eagerly waiting for the charge from the Japanese fleet.
The second one is that the navy officers neglected not only intelligence but also technology. While Japanese navy were preparing the operation against the island, they found it took too much time to change bombs equipped on attacking planes to torpedo or vice versa. Mr. "M", a short term navy technical officer, who was at the navy fleet management headquarter, was appointed to be a responsible engineer for the problem. He made time study of whole routine operations for taking out bombs or torpedo from the magazine and lifting up them to the flight deck, or vice versa, and he discovered that it was wasted too much time for unloading bombs from lifts. By improving the bomb-holder shape of lift, the replacing time which took two hours would be reduced dramatically only to thirty minutes, he found. He recommended his discovery should be adopted immediately. He added it would take only four days to complete the repair works, But the regular officers neglected his proposal and the combined fleet left for the operation without making any improvements of the lifts. Mr. "M"told me if his proposal was adopted, the air battles off the Wake Island would be resulted at least in tie, not in the complete defeat.
The Japanese transport ships were attacked and sunk successively by USS submarines. Because the Marine Code had been deciphered completely by U.S.Navy while Japanese did not acknowledge it throughout the war. Furthermore the headquarters, which managed marine transport ,demanded their transporters to report their location at a fixed time everyday. The enemy could get almost perfect information about the move and location of transport ships. A newly built giant aircraft carrier was sunk by an enemy submarine on her way from the Yokosuka naval base to the Kure naval yard in order to be rigged. This means that not only marine code but navy code was decoded, but the navy did not pay attention on it. Not only Admiral Isoroku Yamamoto, the commander in chief of the combined fleets, but also Admiral Mineichi Koga, the succeeding commander to Admiral Yamamoto, was shot down to death while both of them were riding on planes. Because the navy code was deciphered. During the battle of Okinawa, the most of Japanese suicide attack planes could not get trough the bullets curtains by U.S. forces and were shot down before they could reach their target warships. Because the bullets of U.S. forces had special fuses which explode bullets when they came up to the near of the enemy planes. If the commanders of naval air base went to the battle sea together with special planes in order to confirm the results of attacks, he might be able to observe the enemy bullets were somewhat different from conventional bullets.
There were many evidences to prove their codes were broken by the enemy. Still they did not realise it until after the end of war. They could not guess that the new technology was adapted by their enemy. The Imperial Japanese Navy had not the ability for fighting the modern wars.