NPR logo A Pearl Harbor Timeline


A Pearl Harbor Timeline

The following is a timeline of selected events leading up to, and following, the Japanese attack on Pearl Harbor.

The USS Shaw was destroyed when its magazine detonated in a huge explosion. National Archives hide caption

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July: Japan invades North China from Manchuria.


July: U.S. imposes trade sanctions, followed by an embargo, aimed at curbing Japan's military aggression in Asia.


January: Adm. Yamamoto begins communicating with other Japanese officers about a possible attack on Pearl Harbor.

Jan. 27: Joseph C. Grew, the U.S. ambassador to Japan, wires Washington that he has learned that Japan is planning a surprise attack on Pearl Harbor. No one in Washington believes the information. Most senior American military experts believe the Japanese would attack Manila in the Philippine Islands if war broke out.

February: Adm. Husband E. Kimmel assumes command of the U.S. Pacific Fleet in Hawaii. Kimmel and Lt. Gen.Walter C. Short, commanding general of the Hawaiian Department, prepare for the defense of the islands. They ask their seniors in Washington for additional men and equipment to insure a proper defense of military instillations.

April: U.S. intelligence officers continue to monitor Japanese secret messages. In a program code-named Magic, U.S. intelligence uses a machine to decode Japan's diplomatic dispatches. Washington does not communicate all the available information to all commands, including Short and Kimmel in Hawaii.

May: Japanese Adm. Nomura informs his superiors that he has learned Americans were reading his message traffic. No one in Tokyo believes the code could have been broken. The code is not changed.

July: Throughout the summer, Adm. Yamamoto trains his forces and finalizes the planning of the attack on Pearl Harbor.

Sept. 24: The "bomb plot" message from Japanese naval intelligence to Japan's consul general in Honolulu requesting a grid of exact locations of ships in Pearl Harbor is deciphered. The information is not shared with the Hawaii's Adm. Kimmel and Gen. Short.



Nov. 16: Submarines, the first units involved in the attack, depart Japan.

Nov. 26: The main body, aircraft carriers and escorts, begin the transit to Hawaii.

Nov. 27: Kimmel and Short receive a so-called "war warning" from Washington indicating a Japanese attack, possibly on an American target in the Pacific, is likely.

Night of Dec. 6, Morning of Dec. 7: U.S. intelligence decodes a message pointing to Sunday morning as a deadline for some kind of Japanese action. The message is delivered to the Washington high command before 9 a.m. Washington time, more than 4 hours before the attack on Pearl Harbor. But the message is not forwarded to the Pearl Harbor commanders and finally arrives only after the attack has begun.

At 0755, Hawaiian time, the first wave of Japanese aircraft begin the attack. Along with the ships in Pearl Harbor, the air stations at Hickam, Wheeler, Ford Island, Kaneohe and Ewa Field are attacked.

The Japanese attack continues for two hours and 20 minutes. When it's over, more than 2,400 Americans are dead and nearly 1,200 wounded. Eighteen ships have been sunk or damaged. More than 300 aircraft are damaged or destroyed.

Dec. 8: President Roosevelt addresses Congress and asks for a declaration of war against Japan, which he receives.

Dec. 16: Adm. Kimmel and Gen. Short are relieved of their commands.


January: The Roberts Commission appointed by President Roosevelt finds Kimmel and Short in dereliction of duty and solely responsible for the Pearl Harbor disaster.


January: Capt. Laurence Safford, the Navy's former chief cryptographer, discovers that officials in Washington withheld secret information from Kimmel and Short.

October: A Naval Court of Inquiry finds Kimmel had not been derelict but had acted appropriately given what he knew. The Chief of Naval Operations overrules the court, saying if Kimmel had done aerial reconnaissance he might have discovered the Japanese fleet just 250 miles off Hawaii.


December: A Defense Department investigation finds others share the responsibility with Kimmel and Short for the Pearl Harbor disaster. It does not say who those "others" are.


An amendment to the Defense Appropriations Act of 2001 finds Kimmel and Short acted competently and professionally and urges the president to restore the officers to their highest WWII rank.
