On December 7, 1941, Japanese planes attacked the U.S. Naval Base at Pearl Harbor, Hawaii Territory, killing more than 2,300 Americans. (The spectacular explosion of the U.S.S. Shaw’s forward magazine provided one of the most iconic photographs of the day.)
The U.S.S. Arizona was completely destroyed and the U.S.S. Oklahoma capsized. A total of twelve ships sank or were beached in the attack and nine additional vessels were damaged. More than 160 aircraft were destroyed and more than 150 others damaged. (The U.S.S. Shaw was repaired in a few months, and served extensively in the Pacific through the rest of World War II, earning eleven battle stars.)
A hurried dispatch from the ranking United States naval officer in Pearl Harbor, Commander in Chief Pacific, to all major navy commands and fleet units provided the first official word of the attack at the ill-prepared Pearl Harbor base. It said simply: AIR RAID ON PEARL HARBOR X THIS IS NOT DRILL.
Read more: http://memory.loc.gov/ammem/today/dec07.html