I've been reading about
the Japanese attack on Pearl Harbor, December 7, 1941, that killed over 2,400 Americans, wounded 1,000 more, and damaged hundreds of warplanes and ships. I've been particularly interested in how the concept of
"groupthink" caused our military to be taken by surprise. I was even more interested to read the definition of the word
"surprise" in the Merriam-Webster dictionary. "Surprise" means "an attack without warning." Based on what I've read, I can't help but ask myself, "Is it really a surprise if there are plenty of warnings?"
The American psychologist
Irving Janis studied the "surprise" attack on Pearl Harbor when he first developed his theory of
"groupthink" (see the chapter in his book,
Groupthink for an in-depth analysis). The signals were there, but unfortunately the U.S. military on Hawaii ignored them. There have been a number of great books on this specific issue that I won't catalog here, though aside from the aforementioned Janis book, I would recommend Roberta Wohlstetter's book
Pearl Harbor: Warning and Decision for its depth of analysis of this unfortunate incident in American military history.
So, what were the missed warnings? Before I catalog them, it's important to provide some historical context. First, it's important to remember that Japan and the United States were allies during World War I, and by the conclusion of that war Japan's military had taken control of German bases in China and the Pacific. With the signing of the
Treaty of Versailles, Japan was given a League of Nations mandate (
"South Seas Mandate") over the German colonial possessions north of the equator, with Australia getting those south of the equator. With that mandate,
Japan had officially become a Great Power (see also Paul Kennedy's book,
The Rise and Fall of the Great Powers).
Shortly after the war, the world's largest naval powers gathered in Washington, D.C. for a conference (called, appropriately enough,
the Washington Naval Conference of 1921-1922) to discuss naval disarmament. The
Five-Power Treaty was signed by the United States, the United Kingdom, Japan, France, and Italy which called for each of the countries to maintain a set ratio of capital warship tonnage at a 5:5:3 ratio (the U.S. was allowed 500,000 tons, the United Kingdom was allowed 500,000 tons, Japan was allowed 300,000 tons, and France and Italy were each allowed 175,000 tons). In reality, in order to meet these limits, the U.S. had to reduce its number of capital ships and cease further building of new ones, while Japan was able to significantly increase the size of its Navy. The United States, France, the United Kingdom, and Japan further agreed to consult with each other in the event of any future crisis in East Asia, and additional countries (Italy, Belgium, the Netherlands, Portugal, and China) agreed that to respect the territorial integrity of China, consistent with the
U.S. Open Door Policy.
For a time, the status quo in the Pacific remained peaceful. However, Japan continued to build up its military and slowly expand into China, which led to the Second Sino-Japanese War in 1937 and the infamous
"Rape of Nanking", both of which were universally condemned by the U.S. and several members of the League of Nations. The
USS Panay Incident that same year, in which the Japanese bombed U.S. Navy river gunboat and three Standard Oil Company tankers who were attempting to rescue U.S. and Chinese civilians fleeing Nanking, further escalated tensions between the U.S. and Japan.
Several countries were focused on Adolf Hitler's aggressive actions in Europe, and Japan took full advantage of this loss of attention in the Pacific. Japan invaded French Indochina, continued its war in China, and signed the
Tripartite Pact with Italy and Germany in 1940. The U.S. responded by initiating an iron, steel, and oil embargo on Japan, and the Japanese military started making plans to go to war with the U.S. in the Pacific.
Marshal Admiral Isoroku Yamamoto, Commander-in-Chief of the Combined Fleet of Japan came up with the strategy calling for simultaneous attacks on British, Dutch, and U.S. territories in the Pacific. His plan included a surprise attack on the U.S. Navy's base in Pearl Harbor, Hawaii, with the goal of disabling the U.S. Pacific Fleet for a period of six months, giving time for Japan to negotiate a peace settlement in their favor (and keeping all of their acquisitions).
With all of that historical context, we can go back and review all of the missed warning signals. Most importantly, the U.S. military had been preparing for a potential war with Japan for several years, and with Japan's increasingly aggressive posture and military actions in the Pacific, the likelihood of that war had increased significantly. As early as 1924, legendary Army hero
Billy Mitchell, widely regarded as the "Father of the U.S. Air Force" had
predicted a war with Japan, even providing specific details on how that war would begin. He stated that Japan would carry out a surprise attack on Hawaii, predicting that 100 bombers would attack the naval base there. The Army and Navy conducted a series of war games in 1932, in which Pearl Harbor was successfully "attacked" by 152 planes a half-hour before dawn on a Sunday. Later, in 1938, Colonel (then)
George Patton wrote a report titled "Surprise" which outlined how the Japanese would attack Pearl Harbor before officially declaring war. That same year, Admiral
Ernest King led a carrier-born air strike from the USS Saratoga against Pearl Harbor in war games, achieving complete surprise and total victory. Finally, earlier in 1941, the U.S. Secretary of the Navy listed the three dangers to Hawaii "in order of importance and probability... (1) air bombing attack, (2) air torpedo plane attack, and (3) sabotage." In other words, some of the leading military experts at the time had all but predicted that war with Japan was likely inevitable and further how that war would begin - with a surprise air attack.
Just simply being aware of these predictions should have raised
situational awareness in the military leaders on the island of Hawaii in 1941, but apparently it did not, at least not to the degree required. But there were other signals too.
Joseph Grew, the U.S. Ambassador to Japan, learned of Japan's plans to bomb Pearl Harbor from contacts at the Peruvian Embassy as early as January, 1941. Britain's
Lord Louis Mountbatten had also predicted a surprise attack by Japan and visited Pearl Harbor in October, 1941. He was reportedly shocked at the lack of preparations there. Finally, American cryptographers (Operation Code Name Magic) intercepted and decoded a message between the Japanese government and its diplomats who were negotiating for peace with the U.S. government in Washington, D.C. on November 22, 1941 that stated, "...after November 29, things are automatically going to happen". Another message from Japan was intercepted and decoded, informing Germany of imminent war "through some clash of arms" on November 30, 1941.
Approximately one week before the fateful day of December 7, 1941,
Admiral Husband E. Kimmel, Commander-in-Chief of the Pacific Fleet was asked about the odds of Japan attacking Hawaii and replied, "I should say none." On December 2, 1941, U.S. Naval Intelligence lost contact with the Japanese fleet and suggested that they had potentially returned to home waters. Kimmel famously responded, "For all you know, they could be coming around Diamond Head, and you wouldn't know it?" Finally, Kimmel hosted a dinner party the night before the attack, at which Fanny Halsey, wife of
Admiral William "Bull" Halsey who was out to sea at the time stated that she was certain that the Japanese were going to attack. One of the dinner guests famously replied, "We all thought she was crazy." Again, the U.S. military leadership continued to ignore a number of signals pointing to an imminent attack.
Finally, on the actual day of the attack, there were a number of warning signs that could have (and probably should have) prompted a different response. Early in the morning (3:20 AM) on December 7, 1941, the minesweeper USS Condor reported a periscope sighting at the entrance to Pearl Harbor to the destroyer USS Ward. There were no additional sightings despite an active search. Later that morning at 6:30 AM, the stores ship USS Antares reported another submarine sighting to the USS Ward, which actually fired upon the submarine (later revealed to be a Japanese mini-submarine). They sent a report to the Pacific Fleet headquarters, "We have attacked, fired upon, and dropped depth charges on a submarine operating in the defensive area." The duty officer at headquarters chose to wait until further verification before sounding the alarm.
There were five radar locations on the island of Oahu, and only the Opana site was still operational by 7 AM on December 7, 1941 (radar was still a relatively new technology and these stations only operated at certain hours of the day). Army privates Joseph Lockard and George Elliot tracked the incoming first wave of Japanese aircraft from 7:02 AM to 7:40 AM. They notified their duty officer, LT Kermit Tyler at nearby Fort Schafter, who assumed that the radar signal was an expected incoming flight of B-17 bombers that were due to arrive from the West Coast.
The first attack wave commenced at 7:55 AM and found the U.S. Pacific Fleet to be completely unprepared. As a matter of fact, despite all the aforementioned predictions, the Army was more concerned about sabotage and had parked all of its planes close together to prevent that kind of attack. In retrospect, this only made the air attack more successful.
