On December 7th, at 7:40 a.m. Hawaii Time, Mitsuo Fuchida fired a single “black dragon” from a signal pistol he carried in his aircraft. 
This was a signal to the other planes in his formation that they were to commence the attack on Pearl Harbor under the configuration of having achieved surprise. Nine minutes later Fuchida ordered his radioman to send a single message back to the fleet, “To, to, to, to…” signaling that they had achieved surprise on the American forces below. The story from there is one very well known to just about anyone. The Japanese commenced on a devastating attack on the U.S. Fleet at Pearl Harbor that sank or damaged every battleship in the harbor along with several other vessels. The action catapulted the United States into war with Japan to which Germany obliged their ally by declaring war on America a few days later. The final major player in the Second World War was now an official combatant in a conflict that would shape the world for generations to come.
Before the fires on the ships at Pearl Harbor were even put out questions began to fly as to how it was possible for the Japanese to successfully attack the U.S. Fleet. Investigations were launched into the events leading up to the attack beginning with the Roberts Commission, which was formed by executive order on December 18th, 1941. Throughout the war and even after its conclusion investigations continued to try and piece together what went wrong in the American chain of command and who should be held accountable for the failure of that day. Among those investigations, Henry C. Clausen was appointed as a special investigator by Secretary of War Henry Stimson in 1945 to follow up on the recently completed Army Board hearings.
In Clausen’s book, Pearl Harbor: Final Judgement, Clausen goes into the details that made up his investigation into the Pearl Harbor attack. Unlike other investigations which consisted of a board that required witnesses to travel to Washington to testify, Clausen handled his work as a special investigator by travelling to the locations where many of the key players were currently stationed. Since at the time of his investigation, the war in both Europe and Japan were still in progress, this led him to many different locales including ones that put him very near where active combat was still underway. Since Clausen carried with him key MAGIC decrypts to show some of those he would interview, he was forced to wear a bomb pouch so that in the event that he might get captured he would be able to destroy the documents to avoid their capture. To Clausen’s dismay, the pouch was also designed to destroy him with the documents had he ever needed to activate it.
This book is an interesting look into the process of discovery in one of the investigations into the Pearl Harbor attack. In it the author takes the reader on the journey that he took and the processes he used to get his testimony that would eventually end up in the Clausen Report, Volume 35 of the Pearl Harbor hearings. Since he was trying to clear up problems with the Army Board he was often faced with interviewing people who were believed to have perjured themselves in the previous hearings. Many of these men had been evasive during the Army Board hearings in order to protect the secret that the U.S. had broken the Japanese diplomatic codes and had made their prior statements with the thought of protecting MAGIC. It was only when they were shown by Clausen that he was cleared for MAGIC by producing the decrypts he carried with him that these people began to change their story. At the end of the book he takes the time to list the fourteen people that he feels are most responsible for the attack on Pearl Harbor along with an explanation as to how he has come to that conclusion. Additionally, he takes the time to point out the issues with the intelligence system in general which proved to be a major contributor to Pearl Harbor’s failure to defend itself.
There is not much in the way of notation in the body of this book for understandable reasons. This book is after all a first hand account of the Clausen investigation as told by the man himself. However, in places where Clausen or his co-author Bruce Lee, make reference to items that are not first hand accounts they are notated as a footnote on the page where they are mentioned. Additionally, Clausen provides over 150 pages of documentation that he has felt to be of vital interest on the events leading up to the attack. This appendix is full on interesting information that includes the documents that Clausen took with him on his investigation as well as many key exchanges between Washington and Hawaii. It also has many of the MAGIC decrypts including ones that would have been very telling but unfortunately were not translated until after the attack.
For those interested in learning more on the events leading up to the Pearl Harbor attack I would recommend this book. It should be noted that as with any first person account there will naturally be a degree of bias towards the individual as is human nature. However, this book is very detailed on the process and the singular appendix of documentation alone makes it a very good resource for determining what factors played a roll in the failure at Pearl Harbor.
CougarGA7