It was a sunny, mostly clear Sunday in Pearl Harbor on Dec. 7, 1941, when the unexpected hum of planes cut through the warm Hawaiian air. In a period of just two hours, 353 Japanese aircraft laid siege to the U.S. naval base, sinking 18 ships and destroying nearly 200 aircraft in a sneak attack that killed more than 2,400 Americans and wounded over 1,000 more.
The photos below show the severity of the destruction and why the tragedy led the U.S. to get involved in World War II:
Believed to be the first bomb dropped on Pearl Harbor, Hawaii in the sneak-attack on Dec. 7, 1941, this picture was found torn to pieces at Yokusuka Base by photographer's mate 2/C Martin J. Shemanski of Plymouth, Pa. One Japanese plane is shown pulling out of a dive near bomb eruption (center) and another the air at upper right. (AP Photo)
A Japanese bomber on a run over Pearl Harbor, Hawaii is shown during the surprise attack of Dec. 7, 1941. Black smoke rises from American ships in the harbor. Below is a U.S. Army air field. (AP Photo)
In this Dec. 7, 1941 file photo, the destroyer USS Shaw explodes after being hit by bombs during the Japanese surprise attack on Pearl Harbor, Hawaii. (AP File Photo)
USS Shaw's magazine explodes during attack.
Sailors watch as the USS Shaw explodes.
This Dec. 7, 1941 image shows a Japanese Navy aerial view of smoking U.S. ships during the attack on Pearl Harbor, Hawaii. (AP Photo/Japanese Navy)
In this image provided by the U.S. Navy, U.S. sailors man boats at the side of the blazing USS West Virginia to fight the flames started by Japanese torpedoes and bombs on the battleship at Pearl Harbor, Hawaii on Dec. 7, 1941. The Stars and Stripes fly bright against the smoke-blackened sky over the harbor. (AP Photo/U.S. Navy)
Torpedoed and bombed by the Japanese, the battleship USS West Virginia begins to sink after suffering heavy damage, center, while the USS Maryland, left, is still afloat in Pearl Harbor, Oahu, Hawaii, Dec. 7, 1941 during World War II. The capsized USS Oklahoma is at right. (AP Photo/U.S. Navy)
Students of the Lunalilo High School in the Waikiki district of Honolulu watch their school burn after the roof of the main building, at center, is hit by a bomb during the Japanese bombing of Pearl Harbor, Hawaii, on Dec. 7, 1941. (AP Photo)
Three U.S. battleships are hit from the air during the Japanese attack on Pearl Harbor on Dec. 7, 1941. Japan's bombing of U.S. military bases at Pearl Harbor brings the U.S. into World War II. From left are: USS West Virginia, severely damaged; USS Tennessee, damaged; and USS Arizona, sunk. (AP Photo)
Japanese planes over Hawaii during the attack on Pearl Harbor, Dec. 7, 1941, are shown in this scene from a Japanese newsreel. The film was obtained by the U.S. War Department and released to U.S. newsreels. (AP Photo/U.S. War Department)
In this U.S. Navy file photo, a small boat rescues a USS West Virginia crew member from the water after the Japanese bombing of Pearl Harbor, Hawaii on Dec. 7, 1941 during World War II. Two men can be seen on the superstructure, upper center. The mast of the USS Tennessee is beyond the burning West Virginia. On Dec. 7, 1941, Japanese Imperial Navy navigator Takeshi Maeda guided his Kate bomber to Pearl Harbor and fired a torpedo that helped sink the USS West Virginia. President Barack Obama on Thursday Dec. 6, 2012 issued a proclamation declaring Dec. 7 a day of remembrance in honor of the 2,400 Americans who died at Pearl Harbor. He urged federal agencies, organizations and others to fly their flags at half-staff. (AP Photo, File)
A column of black smoke rises from the U.S. Navy base in Pearl Harbor, Oahu, Hawaii at 7:55 a.m., Sun., Dec. 7, 1941 as Japan declared war against the United States. Bombs exploding over "Battleship Row," awakened Mrs. Mary Naiden of New York City, who was serving as a hostess at the Army's Hickam Field. She thought a U.S. plane had crashed into a gasoline or oil depot and took this photo without leaving her room. (AP Photo/Mary Naiden)
Smoke rises from a hangar.
Struck by two battleships and two big bombs, the USS California, right, settles to the bottom during the Japanese sneak attack on Pearl Harbor on Dec. 7, 1941 during World War II. (AP Photo)
Black smoke pours from the U.S. Destroyer USS Shaw after a direct hit by bombs during the surprise aerial attack by the Japanese on Pearl Harbor, Hawaii, on Dec. 7, 1941. Defenders on the pier at left throw water into the blazing wreckage. (AP Photo/U.S. Navy)
Rescue workers help evacuate the Lunalilo High School in Honolulu after the roof of the main building was hit by a bomb during the Japanese attack at Pearl Harbor, Hawaii on Dec. 7, 1941. (AP Photo)
Concentric waves are traced by the direct torpedo hits from Japanese bombs, while murky crude oil flows out, Dec. 7, 1941. The three bright white streaks between the waves are the torpedo tracks. In the distance the conflagration at the field hangars is seen. (AP Photo)
In this photo provided by the U.S. Navy, it was just another bright sunny Sunday morning at Pearl Harbor Naval Base on December 7. Then, all of a sudden, came a hail of Japanese bombs and machine gun fire, leaving the burning battleship USS Arizona sinking in the harbor, along with four other warships destroyed on Dec. 7, 1941. (AP Photo)
In this image provided by the U.S. Navy, a pall of smoke filled the sky over Pearl Harbor, Hawaii on Dec. 7, 1941, after the Japanese attacked. In the foreground is the capsized minelayer, the USS Oglala, and to the left appears the moored USS Helena, 10,000-ton cruiser, struck by a bomb. Beyond the superstructure of the USS Pennsylvania, and at the right is the USS Maryland, burning. At right center the destroyer Shaw is ablaze in drydock. (AP Photo/U.S. Navy)
In this image provided by the U.S. Department of Defense, destroyers in drydock at Pearl Harbor in Hawaii are battered by bombs after Japanese sneak attack on Dec. 7, 1941. Background in dock is battleship Pennsylvania, which suffered only minor damage. Destroyers are Downes, left, and Cassin, right. Machinery and fittings were transferred to new hulls and the destroyers were never stricken from Navy's active list. (AP Photo/U.S. Department of Defense)
In this image provided by the U.S. Army, the wreckage of a Japanese bombing plane shot down near a CCC camp, Hawaii during the raid on Dec. 7, 1941. (AP Photo/U.S. Army)
In this photo provided by the U.S. Navy, giant hangar at the U.S. Naval Air Station at Pearl Harbor is fringed in flames caused by Japanese bombs which wrecked the installation, Dec. 7, 1941. Planes on aprons and runways were burned and shattered. Wreckage of some may be seen in foreground. (AP Photo/U.S. Navy)
In this photo provided by the Department of Defense, U.S. aircraft destroyed as a result of the Japanese bombing on Pearl Harbor is shown, Dec. 7, 1941. Heap of demolished hanger in background Army amphibian in foreground. (AP Photo/DOD)
The 7 December 1941 Japanese raid on Pearl Harbor was one of the great defining moments in history. A single carefully-planned and well-executed stroke removed the United States Navy's battleship force as a possible threat to the Japanese Empire's southward expansion. America, unprepared and now considerably weakened, was abruptly brought into the Second World War as a full combatant.
Eighteen months earlier, President Franklin D. Roosevelt had transferred the United States Fleet to Pearl Harbor as a presumed deterrent to Japanese aggression. The Japanese military, deeply engaged in the seemingly endless war it had started against China in mid-1937, badly needed oil and other raw materials. Commercial access to these was gradually curtailed as the conquests continued. In July 1941 the Western powers effectively halted trade with Japan. From then on, as the desperate Japanese schemed to seize the oil and mineral-rich East Indies and Southeast Asia, a Pacific war was virtually inevitable.
By late November 1941, with peace negotiations clearly approaching an end, informed U.S. officials (and they were well-informed, they believed, through an ability to read Japan's diplomatic codes) fully expected a Japanese attack into the Indies, Malaya and probably the Philippines. Completely unanticipated was the prospect that Japan would attack east, as well.
The U.S. Fleet's Pearl Harbor base was reachable by an aircraft carrier force, and the Japanese Navy secretly sent one across the Pacific with greater aerial striking power than had ever been seen on the World's oceans. Its planes hit just before 8AM on 7 December. Within a short time five of eight battleships at Pearl Harbor were sunk or sinking, with the rest damaged. Several other ships and most Hawaii-based combat planes were also knocked out and over 2400 Americans were dead. Soon after, Japanese planes eliminated much of the American air force in the Philippines, and a Japanese Army was ashore in Malaya.
These great Japanese successes, achieved without prior diplomatic formalities, shocked and enraged the previously divided American people into a level of purposeful unity hardly seen before or since. For the next five months, until the Battle of the Coral Sea in early May, Japan's far-reaching offensives proceeded untroubled by fruitful opposition. American and Allied morale suffered accordingly. Under normal political circumstances, an accommodation might have been considered.
However, the memory of the "sneak attack" on Pearl Harbor fueled a determination to fight on. Once the Battle of Midway in early June 1942 had eliminated much of Japan's striking power, that same memory stoked a relentless war to reverse her conquests and remove her, and her German and Italian allies, as future threats to World peace.