World War II (1939–1945): Japan and Pearl Harbor

Previous Next

In addition to attacking Pearl Harbor that day, Japan also attacked the U.S. territories of Guam, the Philippines, Wake Island, and Midway Island, as well as British interests in Malaya and Hong Kong.

Declarations of War

The next day, December 8, Roosevelt went before both houses of the U.S. Congress to request a declaration of war against Japan; after a vote, the declaration was formalized just hours later. Britain declared war on Japan on the same day. Three days later, on December 11, Germany declared war on the United States. Thus, the United States was now at war with both Japan and Germany and able to enter fully into its alliance with Britain.

Reaction in the United States

The story of the attack on Pearl Harbor has become a part of American culture. For the American population, the event was a traumatic shock, as few regular Americans knew much about the events in Japan leading up to the war or about the level of hostility that Japan bore toward the United States. Officials in the U.S. government, however, could not claim such obliviousness. Uncomfortable questions were soon raised in Congress and on the streets about why the United States had been so poorly prepared and why the U.S. intelligence services had failed to see the attack coming or raise warnings earlier.

Over the years, historical analysis has shown that there were many warning signs in the months before the attack and that some U.S. military leaders, most notably Admiral Turner, had been concerned that the Pearl Harbor base was particularly vulnerable to attack. Furthermore, the United States was able to decode and read Japanese military communications until shortly before the attack, when Japan abruptly changed its military codes. By the evening of December 6, 1941, U.S. military and government officials, including President Roosevelt, were certain that Japan was planning a major action against U.S. interests. A meeting was even scheduled for 3:00p.m. on December 7 to discuss the matter. Unfortunately, the target of the attack was unknown, and no one at Pearl Harbor was notified to be on alert.

To this day, there is avid speculation about how much the United States could and should have done to prevent the attack, and even more speculation over how much the United States and its allies knew about Japanese plans. Britain’s prime minister, Winston Churchill, was desperate for active U.S. participation and had long been pressing his old friend Roosevelt to enter the war. Some historians maintain that British intelligence had specific information about the Pearl Harbor attack and that Churchill deliberately kept the information to himself so that the United States would finally go to war. These claims, however, remain unconfirmed.