Aaron O'Neill
Research expert covering historical data
WWII: Attack on Pearl Harbor - Statistics & Facts
On the morning of December 7, 1941, the Empire of Japan attacked the United States naval base at Pearl Harbor in Honolulu, Hawaii. The attack lasted just over two hours. It resulted in the deaths of over 2,400 U.S. servicemen and citizens, and inflicted severe damage upon the U.S. Pacific Fleet. The attack came as a major surprise to the U.S., and resulted in one of the most significant developments in recent history – the next day, the U.S. declared war on Japan, and the world’s largest military power had formally joined the Second World War.
Despite this, the United States remained militarily neutral. Due to the seemingly successful recovery from the Great Depression, and geopolitical uncertainty, Franklin D. Roosevelt was elected to an unprecedented third term in office in 1940. A large part of Roosevelt’s popularity was his refusal to join overseas wars, yet, Roosevelt was aware of the threat posed by the Axis powers, and had been providing large amounts of financial and material aid to Britain after the rest of Western Europe fell in mid-1940. Roosevelt also cut trade ties with the Axis powers as their aggression grew, which led to the oil embargo against Japan in August 1941. The U.S. provided over 80 percent of Japan’s oil at the time, ands this was a major blow to Japan’s industrial and military ambitions. The embargo was to be lifted if Japan ceased its aggression in China and East Asia, which the U.S. believed could help bring their expansion to a halt, but it actually had the opposite effect.
As Europe’s colonial powers were preoccupied with war at home, their territories in Southeast Asia became vulnerable - this created both political and economic opportunities for Japan, particularly the oil-rich regions of the Dutch East Indies (Indonesia). The U.S. had gradually bolstered its military presence in the Pacific in the late 1930s, most notably in its territory in the Philippines, and this posed the largest challenge to Japanese expansion. The Japanese also believed that any attack on European territories would bring the U.S. into the war and give them time to prepare and mobilize, therefore a direct attack on the U.S. would give the best opportunity for success.
On November 26, a fleet of 28 ships and 23 submarines set off from Hitokappu Bay, Japan. This force included all six of the Japanese Navy’s aircraft carriers, and was accompanied by eight oil tankers, which allowed the fleet to refuel at sea. The risk of detection by the U.S. military was very high, yet, the risk was rewarded, and after two weeks of sailing the Japanese fleet positioned itself within 300 miles of Pearl Harbor. On the morning of December 7, the U.S. intercepted and destroyed an enemy midget submarine in Hawaiian waters, this was the first shot fired by the U.S. in WWII, but no further defense preparations were made. Even as U.S. radar on the island of Oahu detected an unidentified wave of aircraft at 7:02am, it was mistakenly deemed to be an American training exercise. The first Japanese bombs were dropped at 7:55am.
Alongside the airfields, the other squadrons targeted the naval forces; especially battleships. Six battleships were damaged, while two were destroyed beyond repair. This included the U.S.S. Arizona, where one bomb detonated the ship’s magazine, and the resulting explosion killed 1,177 of the 1,512 personnel on board – this was almost half of all U.S. deaths on the day. Perhaps the only consolation on the day was the fact that the three U.S. aircraft carriers stationed at Pearl Harbor were all at sea that morning, unintentionally avoiding the attack.
The second wave of 171 planes arrived one hour after the first. U.S. defenses were much more prepared during the second wave, and roughly two thirds of Japanese losses occurred during this wave – however, Japanese losses were just a fraction of the damage inflicted upon the U.S.. Just two hours passed between when the first bomb was dropped and the final planes made their way back to the Japanese fleet at around 10am, having changed the course of history forever.
Due to the U.S. high command’s unpreparedness and inaction, the commander in chief of the Pacific Fleet, Husband E. Kimmel, was stripped of his rank and demoted from four star to two star admiral, while the U.S. Army commander in Hawaii, Walter Short, was also relieved of his position – both retired before the war’s end. There was some suggestion that these men were made scapegoats by the Pentagon, and Congress voted to posthumously restore their ranks in 1999, but no president has ever officiated this and the historical consensus does not wholly agree. The U.S.S. Arizona remains sunk in the bay of Pearl Harbor today, and serves as a memorial to those who lost their lives in the attack.
Background
The Second World War is widely considered to have started with Germany's invasion of Poland in September 1939 - by late-1941, most of Europe was occupied or aligned with the Axis powers, and the Germans were moving rapidly toward Moscow. Meanwhile in Asia, the Japanese invasion of China (a U.S. ally) was entering its fourth year, and the Japanese had cut off U.S. supply lines to China by annexing parts of French Indochina (in present-day Vietnam).Despite this, the United States remained militarily neutral. Due to the seemingly successful recovery from the Great Depression, and geopolitical uncertainty, Franklin D. Roosevelt was elected to an unprecedented third term in office in 1940. A large part of Roosevelt’s popularity was his refusal to join overseas wars, yet, Roosevelt was aware of the threat posed by the Axis powers, and had been providing large amounts of financial and material aid to Britain after the rest of Western Europe fell in mid-1940. Roosevelt also cut trade ties with the Axis powers as their aggression grew, which led to the oil embargo against Japan in August 1941. The U.S. provided over 80 percent of Japan’s oil at the time, ands this was a major blow to Japan’s industrial and military ambitions. The embargo was to be lifted if Japan ceased its aggression in China and East Asia, which the U.S. believed could help bring their expansion to a halt, but it actually had the opposite effect.
As Europe’s colonial powers were preoccupied with war at home, their territories in Southeast Asia became vulnerable - this created both political and economic opportunities for Japan, particularly the oil-rich regions of the Dutch East Indies (Indonesia). The U.S. had gradually bolstered its military presence in the Pacific in the late 1930s, most notably in its territory in the Philippines, and this posed the largest challenge to Japanese expansion. The Japanese also believed that any attack on European territories would bring the U.S. into the war and give them time to prepare and mobilize, therefore a direct attack on the U.S. would give the best opportunity for success.
Pearl Harbor naval base
The U.S. Pacific Fleet was generally based in California, but given the geopolitical situation, the fleet was moved to the middle of the Pacific Ocean in 1940, to the Pearl Harbor naval base in the territory of Hawaii (Hawaii was not made a state until 1959). Pearl Harbor was strategically chosen for the geographic advantages it granted to the navy – it was thousands of miles from the nearest enemy airfield, volcanic mountains created a natural shield around the bay, and the bay itself has an average depth of just 14 meters (45 feet) – all of which provided some protection from attacks from the air, sea, and below the surface.The element of surprise & missed warnings
By November 1941, U.S. intelligence in Washington had identified that an attack was imminent. Military leadership in Hawaii concluded that the likeliest targets would be the Philippines and other colonial territories, which the Pacific Fleet would then support in the event of an attack. When reports of Japanese embassies in the U.S. burning all documents was relayed from Washington, D.C. to naval leadership, it was disregarded as simply the Japanese preparing to be attacked by the U.S, and not the opposite. The element of surprise was crucial to Japan’s success at Pearl Harbor, and the prospect of detection by the U.S. could have ultimately derailed the entire Japanese war plan.On November 26, a fleet of 28 ships and 23 submarines set off from Hitokappu Bay, Japan. This force included all six of the Japanese Navy’s aircraft carriers, and was accompanied by eight oil tankers, which allowed the fleet to refuel at sea. The risk of detection by the U.S. military was very high, yet, the risk was rewarded, and after two weeks of sailing the Japanese fleet positioned itself within 300 miles of Pearl Harbor. On the morning of December 7, the U.S. intercepted and destroyed an enemy midget submarine in Hawaiian waters, this was the first shot fired by the U.S. in WWII, but no further defense preparations were made. Even as U.S. radar on the island of Oahu detected an unidentified wave of aircraft at 7:02am, it was mistakenly deemed to be an American training exercise. The first Japanese bombs were dropped at 7:55am.
The attack
In the first wave, 183 Japanese planes made their way toward Hawaii. The airfields were targeted first to prevent American planes from taking to the skies. Due to paranoia of sabotage at the hands of Japan’s ethnic-Japanese population, the U.S. command had ordered the bulk of the aerial fleet to be kept under surveillance, in the open, on the tarmac – this allowed the Japanese to destroy over 100 planes in just a few minutes. The situation was exacerbated further by the fact that anti-aircraft weapons were also locked away to prevent tampering. Only eight of the more than 400 U.S. planes at Pearl Harbor were able to get airborne during the attack.Alongside the airfields, the other squadrons targeted the naval forces; especially battleships. Six battleships were damaged, while two were destroyed beyond repair. This included the U.S.S. Arizona, where one bomb detonated the ship’s magazine, and the resulting explosion killed 1,177 of the 1,512 personnel on board – this was almost half of all U.S. deaths on the day. Perhaps the only consolation on the day was the fact that the three U.S. aircraft carriers stationed at Pearl Harbor were all at sea that morning, unintentionally avoiding the attack.
The second wave of 171 planes arrived one hour after the first. U.S. defenses were much more prepared during the second wave, and roughly two thirds of Japanese losses occurred during this wave – however, Japanese losses were just a fraction of the damage inflicted upon the U.S.. Just two hours passed between when the first bomb was dropped and the final planes made their way back to the Japanese fleet at around 10am, having changed the course of history forever.
Aftermath
2,403 Americans were killed, over 300 planes and almost 20 major vessels were destroyed or damaged, and the bulk of the Pacific Fleet was knocked out of action for several months. The attack on Pearl Harbor was just one of several Japanese assaults in the Pacific on that morning (these took place on December 8 local time) – neutralizing the Pacific Fleet was the key to these other invasions success. The day after the attack, President Roosevelt delivered his famous “Day of Infamy” speech, at a joint session of Congress – later that day both the House and Senate voted unanimously to declare war on Japan, bringing the U.S. into the war. Half of the ships damaged in Pearl Harbor returned to service within three months, and the bombing of Tokyo began in April 1942.Due to the U.S. high command’s unpreparedness and inaction, the commander in chief of the Pacific Fleet, Husband E. Kimmel, was stripped of his rank and demoted from four star to two star admiral, while the U.S. Army commander in Hawaii, Walter Short, was also relieved of his position – both retired before the war’s end. There was some suggestion that these men were made scapegoats by the Pentagon, and Congress voted to posthumously restore their ranks in 1999, but no president has ever officiated this and the historical consensus does not wholly agree. The U.S.S. Arizona remains sunk in the bay of Pearl Harbor today, and serves as a memorial to those who lost their lives in the attack.
