Prior to Pearl Harbor the Japanese were already attempting to control China through military aggression - they were a warlike nation and their error in attacking Pearl Harbor was the final go-ahead by a divided United States to enter the WWII. Until that time, the European war was a British/French one - and the U.S. was steeped in a terrible depression - how they managed to equip and rebuild their military as they did until the final bombings of Hiroshima and Nagasaki was a testament to what a nation when united in a cause can do. I have heard many times if Japan had resisted their action in 1941, the U.S. may have opted to remain out.
http://www.history.navy.mil/faqs/faq66-1.htm
The road to war between Japan and the United States began in the 1930s when differences over China drove the two nations apart. In 1931 Japan conquered Manchuria, which until then had been part of China. In 1937 Japan began a long and ultimately unsuccessful campaign to conquer the rest of China. In 1940, the Japanese government allied their country with Nazi Germany in the Axis Alliance, and, in the following year, occupied all of Indochina.
The United States, which had important political and economic interests in East Asia, was alarmed by these Japanese moves. The U.S. increased military and financial aid to China, embarked on a program of strengthening its military power in the Pacific, and cut off the shipment of oil and other raw materials to Japan.
Because Japan was poor in natural resources, its government viewed these steps, especially the embargo on oil as a threat to the nation's survival. Japan's leaders responded by resolving to seize the resource-rich territories of Southeast Asia, even though that move would certainly result in war with the United States.
The problem with the plan was the danger posed by the U.S. Pacific Fleet based at Pearl Harbor. Admiral Isoroku Yamamoto, commander of the Japanese fleet, devised a plan to immobilize the U.S. fleet at the outset of the war with a surprise attack.
The key elements in Yamamoto's plans were meticulous preparation, the achievement of surprise, and the use of aircraft carriers and naval aviation on an unprecedented scale. In the spring of 1941, Japanese carrier pilots began training in the special tactics called for by the Pearl Harbor attack plan.
In October 1941 the naval general staff gave final approval to Yamamoto's plan, which called for the formation of an attack force commanded by Vice Admiral Chuichi Nagumo. It centered around six heavy aircraft carriers accompanied by 24 supporting vessels. A separate group of submarines was to sink any American warships which escaped the Japanese carrier force.
Nagumo's fleet assembled in the remote anchorage of Tankan Bay in the Kurile Islands and departed in strictest secrecy for Hawaii on 26 November 1941. The ships' route crossed the North Pacific and avoided normal shipping lanes. At dawn 7 December 1941, the Japanese task force had approached undetected to a point slightly more than 200 miles north of Oahu. At this time the U.S. carriers were not at Pearl Harbor. On 28 November, Admiral Kimmel sent USS
Enterprise under Rear Admiral Willliam Halsey to deliver Marine Corps fighter planes to Wake Island. On 4 December
Enterprise delivered the aircraft and on December 7 the task force was on its way back to Pearl Harbor. On 5 December, Admiral Kimmel sent the USS
Lexington with a task force under Rear Admiral Newton to deliver 25 scout bombers to Midway Island. The last Pacific carrier, USS
Saratoga, had left Pearl Harbor for upkeep and repairs on the West Coast.
At 6:00 a.m. on 7 December, the six Japanese carriers launched a first wave of 181 planes composed of torpedo bombers, dive bombers, horizontal bombers and fighters. Even as they winged south, some elements of U.S. forces on Oahu realized there was something different about this Sunday morning.
In the hours before dawn, U.S. Navy vessels spotted an unidentified submarine periscope near the entrance to Pearl Harbor. It was attacked and reported sunk by the destroyer USS
Ward (DD-139) and a patrol plane. At 7:00 a.m., an alert operator of an Army radar station at Opana spotted the approaching first wave of the attack force. The officers to whom those reports were relayed did not consider them significant enough to take action. The report of the submarine sinking was handled routinely, and the radar sighting was passed off as an approaching group of American planes due to arrive that morning.
The Japanese aircrews achieved complete surprise when they hit American ships and military installations on Oahu shortly before 8:00 a.m. They attacked military airfields at the same time they hit the fleet anchored in Pearl Harbor. The Navy air bases at Ford Island and Kaneohe Bay, the Marine airfield at Ewa and the Army Air Corps fields at Bellows, Wheeler and Hickam were all bombed and strafed as other elements of the attacking force began their assaults on the ships moored in Pearl Harbor. The purpose of the simultaneous attacks was to destroy the American planes before they could rise to intercept the Japanese.
Of the more than 90 ships at anchor in Pearl Harbor, the primary targets were the eight battleships anchored there. seven were moored on Battleship Row along the southeast shore of Ford Island while the USS
Pennsylvania (BB-38) lay in drydock across the channel. Within the first minutes of the attack all the battleships adjacent to Ford Island had taken bomb and or torpedo hits. The USS
West Virginia (BB-48) sank quickly. The USS
Oklahoma (BB-37) turned turtle and sank. At about 8:10 a.m., the USS
Arizona (BB-39) was mortally wounded by an armorpiercing bomb which ignited the ship's forward ammunition magazine. The resulting explosion and fire killed 1,177 crewmen, the greatest loss of life on any ship that day and about half the total number of Americans killed. The USS
California (BB-44), USS
Maryland (BB-46), USS
Tennessee (BB-43) and USS
Nevada (BB-36) also suffered varying degrees of damage in the first half hour of the raid.
There was a short lull in the fury of the attack at about 8:30 a.m. At that time the USS
Nevada (BB-36), despite her wounds, managed to get underway and move down the channel toward the open sea. Before she could clear the harbor, a second wave of 170 Japanese planes, launched 30 minutes after the first, appeared over the harbor. They concentrated their attacks on the moving battleship, hoping to sink her in the channel and block the narrow entrance to Pearl Harbor. On orders from the harbor control tower, the USS
Nevada (BB-36) beached herself at Hospital Point and the channel remained clear.
When the attack ended shortly before 10:00 a.m., less than two hours after it began, the American forces has paid a fearful price. Twenty-one ships of the U.S. Pacific Fleet were sunk or damaged: the battleships USS
Arizona (BB-39), USS
California (BB-44), USS
Maryland (BB-46), USS
Nevada (BB-36), USS
Oklahoma (BB-37), USS
Pennsylvania (BB-38), USS
Tennessee (BB-43) and USS
West Virginia (BB-48); cruisers USS
Helena (CL-50), USS
Honolulu (CL-48) and USS
Raleigh (CL-7); the destroyers USS
Cassin (DD-372), USS
Downes (DD-375), USS
Helm (DD-388) and USS
Shaw (DD-373); seaplane tender USS
Curtiss (AV-4); target ship (ex-battleship) USS
Utah (AG-16); repair ship USS
Vestal (AR-4); minelayer USS
Oglala (CM-4); tug USS
Sotoyomo (YT-9); and
Floating Drydock Number 2. Aircraft losses were 188 destroyed and 159 damaged, the majority hit before the had a chance to take off. American dead numbered 2,403. That figure included 68 civilians, most of them killed by improperly fused anti-aircraft shells landing in Honolulu. There were 1,178 military and civilian wounded.
Japanese losses were comparatively light. Twenty-nine planes, less than 10 percent of the attacking force, failed to return to their carriers.
The Japanese success was overwhelming, but it was not complete. They failed to damage any American aircraft carriers, which by a stroke of luck, had been absent from the harbor. They neglected to damage the shoreside facilities at the Pearl Harbor Naval Base, which played an important role in the Allied victory in World War II. American technological skill raised and repaired all but three of the ships sunk or damaged at Pearl Harbor (the USS
Arizona (BB-39) considered too badly damaged to be salvaged, the USS
Oklahoma (BB-37) raised and considered too old to be worth repairing, and the obsolete USS
Utah (AG-16) considered not worth the effort). Most importantly, the shock and anger caused by the surprise attack on Pearl Harbor united a divided nation and was translated into a wholehearted commitment to victory in World War II.
