Pearl Harbor, Did We Know About The Attack Beforehand?

The document at the end of this article indicates that the Department of the Navy had checked the disposition of the Japanese forces in 1941 and decided that they were not deployed for an attack on Pearl Harbor. As we know a viscous attack did occur on 7 December 1941. There had been many warnings about an attack, but each one was disregarded and given no credence. Code breakers were ordered to concentrate on the diplomatic traffic rather than the naval chatter from Japan, when in truth it should have been the other way around. While the attack on Pearl Harbor was not supposed to happen before a declaration of war, it wouldn't have made much difference, since the attack was originally scheduled to happen only a short time after the declaration of war. The problem had been that the Japanese embassy had taken too long to decode the declaration of war and missed their deadline, by which they were supposed to have served it on the U.S.

Japanese Carrier
Japanese Carrier Akagi
Photo Source: USN

The U.S. was quite confident that Pearl Harbor was too shallow for a torpedo run by aircraft, so they were not as worried as they should have been. Little did they know that the Japanese had developed a shallow running torpedo that was quite capable of sinking any and all of our ships. In one way we were very lucky that poor planning by the Japanese not only saved our carriers, but saved the west coast from bombing runs. If the Japanese had waited for our carriers to have been at Pearl Harbor, the result of the war could have turned out to have been different. The fact that they didn't realize that after their run on Pearl, that the entire west coast of the U.S. was vulnerable was also a large plus for us.

Ignoring radar sightings of a fleet of planes coming in for an attack run, business as usual was conducted at Pearl Harbor, until it was too late. What many people don't realize is that all but two ships had been salvaged from the Pearl Harbor attack. It took until February 1942 to finish the job, a mere three months. The two ships that could not be salvaged were the target ship Utah and the Battleship Arizona. Over 5,000 dives were made that lasted over 20,000 hours to accomplish the task.


Wrecks of USS Downes & Cassin
Photo Source: USN

On January 27, 1941, the U.S. Ambassador to Japan, Joseph C. Grew sent the U.S. State Department a cablegram that stated, “the Japanese military forces planned to attempt a surprise mass attack on Pearl Harbor.” U.S. intelligence dismissed this as a wild rumor. In December 1941 radio silence had been ordered for all Japanese ships. This worried Lt. Commander Edwin T. Layton so much that he went to Admiral Kimmel who was shocked, but did not do much with this information.

Ten official inquiries were conducted into how we could have been attacked at Pearl Harbor without knowing it. The last official inquiry took place in 1995. All ten reported that incompetence was one of the main factors, followed by underestimation and misapprehension of Japanese capabilities and intentions. Other reasons were excessive secrecy, something that goes on today and a lack of intelligence personnel In other words the intelligence community was short of people. Investigators were repeatedly lied to which hindered the investigations. At one time the code breaking facilities had been shut down by Henry Stimson the Secretary of State under Hoover as being unethical. A book was written about American code breaking and every nation revamped their codes because of this and we had to start over.

Battleship Row December 10, 1941

Battleship Row Three Days After The Attack
Photo Source: USN

Before the attack on Pearl Harbor it turned out that the U.S. had already broken several Japanese codes, but not all of them. The British and Dutch had agreed to share the code breaking and routinely gave us information. It has been said the U.S. refused to share what it found out. The U.S. was so paranoid that it restricted sharing of information between the U.S. Navy and U.S. Army. When the U.S. broke the Japanese Purple code, the one that was used most frequently, the commissions could not get all the messages. Some experts believe that we had already broken this code known as JN25 before the Pearl Harbor attack. If this is true than we knew the attack was coming and let it happen. There are many people that say we wanted to get into the war and the British wanted us in it and were egging Roosevelt on to get him in it. There is no doubt that they needed the additional manpower and supplies.

The liner SS Lurline was sailing from San Francisco to Hawaii and heard a lot of radio traffic heading toward Hawaii. It monitored this traffic for several days and noted it was moving east. They figured out that the signals were Japanese by the rhythmic sound of the dots and dashes and it is said that this is the way an experienced radio operator of the time could tell what language code was in, even if they couldn't read it. The Japanese deny sending messages, so this is a mystery and could be accounted for by the fact that the Japanese fleet was receiving a great many messages even though they may not have been transmitting. It is known today that signals can reflect off antennas and this might have been what the SS Lurline was receiving.

USS Shaw

USS Shaw In Drydock
Photo Source: USN

It is said that Jonathan Daniels the administrative assistant to President Roosevelt said he overheard the President being told the following, "The blow was heavier than he had hoped it would necessarily be. ... But the risks paid off; even the loss was worth the price. ...". The U.S. Secretary of War, Henry L. Stimson is said to have met with President Roosevelt 10 days before Pearl Harbor and entered the following statement into his diary, "...how we should maneuver them [the Japanese] into the position of firing the first shot without allowing too much danger to ourselves." Many in the government in those days felt that only a direct attack would sway the American public into getting into the war and specifically on the side of the British. The British wanted our aid in fighting Germany, which they felt was the greatest threat and were hoping that the Japanese would calm down.

Did we know that Pearl Harbor was going to be attacked before it was? Did we desire it to be attacked? Were we being maneuvered into a war status by a group in the government? Did we detect the Japanese fleet before it got to Pearl Harbor and is that why no aircraft carriers were there? There is much proof that Roosevelt was chaffing at the bit to declare war on Germany, but did others also force Japan into a position that took away their access to oil so that they would attack? These burning questions may never be answered fully. There are arguments on both sides of the question. The situation that existed does show however, that if a few in a position of power in the government wanted to, they could certainly cause a war. Does this remind anyone of Iraq?


Pearl Harbor Naval Document

Article Comment
Try Our New Discussion Board