7 December 1941

The Attack on Pearl Harbor conducted by the Imperial Japanese Navy against the United States naval base in the Hawaiian Archipelago has remained one emblematic event of World War 2.

Japanese Gamble

The Japanese military expansion in French Indochina had caused the cease of American oil exports to Japan in July 1941. Due to Japan's dependence of external raw materials, especially petroleum, the American decision fueled even more the plans of expansion in Southeast Asia taken by the decision-makers in Tokyo.

However, the U.S. Pacific Fleet based at Pearl Harbor was a deterrent against the Japanese militarism. So the Japanese devised a plan to attack the American fleet at Pearl Harbor which, they thought, if successful would have facilitated their dominance of Southeast Asia and Western Pacific.

In late November 1941, the Japanese sent towards Pearl Harbor a striking force whose core was made up of six aircraft carriers. 350 Japanese planes took part in the raid on Pearl Harbor: 143 Nakajima B5N "Kate" level/torpedo bombers, 129 Aichi D3A "Val" dive-bombers and 78 Mitsubishi A6M "Zero" fighters.

Derivative work by Wallach79, original file: Historicair [CC BY-SA 3.0 (], via Wikimedia Commons

Surprise Effect and Yet Luck

On the morning of December 7, 1941, the Japanese planes took off in two waves from the carriers positioned north of Hawaii. A U.S. radar on the island of Oahu of the Pearl Harbor base detected the Japanese planes, but the Americans assumed they were B-17 bombers that were to arrive on the island.

The unexpected attack came as a shock as the air defense, both on ships and on the island, was at a very low readiness level, understaffed and with unprepared ammunition. The few U.S. fighters that were in the air were shut down by the Japanese aircraft.

The capital ships of the U.S. Pacific Fleet - battleships and aircraft carriers - were to be targeted by Nakajima B5N bombers, armed with armor-piercing bombs of 800 kg (1760lb) or torpedoes. The chance of the U.S. Navy was that no aircraft carrier was at Pearl Harbor at that time.

Aftermath of the Attack on Pearl Harbor

All eight U.S. battleships which were at Pearl Harbor during the raid were damaged, but only two were totally lost. Because the water had a low level in the port area, most damaged ships were recovered and repaired, re-entering service in the coming months or years.

Airfields on the island were another major target, the Japanese destroying 188 U.S. aircraft, mostly on the ground, while losing only 29 planes.

About 2,400 Americans were killed, most of them sailors, and several hundred were wounded.

If the Japanese had attacked the docks, fuel depots, headquarters building or the submarine base, the U.S. Navy's ability to continue the war probably would have been affected for a longer period.

The Battle of Pearl Harbor resulted in the entry of the United States in World War 2. The Japanese had gambled on a decisive blow, but the following battles would show that they did not achieve the strategic goal.

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