Facts, information and articles about the attack on Pearl Harbor, Hawaii.
Date: December 7, 1941
Location: Oahu, Hawaii
United States: Husband Kimmel and Walter Short
Japanese: Chuichi Nagumo and Isoroku Yamamoto
Outcome: Japanese Victory
Casualties: United States: 3,700 Japanese: 50 civilians: 48-68
Importance: The surprise attack on America led to the nation entering World War II
Explore the HistoryNet archives about Pearl Harbor
Pearl Harbor summary:
On December 7, 1941 the Japanese launched a surprise attack on the US Naval Base Pearl Harbor in Hawaii, using bombers, torpedo bombers and midget submarines. On December 8, President Franklin D. Roosevelt delivered his “Infamy Speech” to American citizens, informing them that this occurred despite the fact that the US was in the midst of talks to keep peace with Japan. That same day, with congressional approval, America entered into World War II.
On the southern end of Oahu, Pearl Harbor held a 22,000 acre naval base. Admiral Husband E. Kimmel of the Navy and Lt. General Walter C. Short of the Army were in command of the fleet and troops on the ground, respectively. The majority of the Pacific area’s military commands were headquartered there because of growing apprehensions regarding an aggressive Japanese presence.
Since Emperor Hirohito’s Japan wanted to expand in territory and power like some European countries, it needed natural resources, like oil and aluminum found in the Netherlands East Indies. Standing in opposition to Japanese conquest of what Japan’s leaders termed “the Southern Resource Area” was the United States. In 1940 the US, Great Britain, and the Netherlands had initiated a total embargo of oil and scrap metal to Japan in response to Japan invading French Indochina. Unless a new source of oil was opened, the Imperial Japanese Navy would be in dry dock within a year and Japanese industries would grind to a halt in 12–18 months.
A plan was developed to cripple the US Pacific Fleet at Pearl Harbor to allow time for Japan to seize the resource areas it needed and fortify them to the point that retaking them would cost more lives than the Imperial High Command thought Americans would be willing to pay. The Pearl Harbor attack plan was conceived by Admiral Isoroku Yamamoto, commander in chief of the IJN. Yamamoto had studied in the United States. He knew his nation lacked the ability to defeat the much larger, resource-and industry-rich country and did not share the opinion of many Japanese officers that the Americans were too weak-willed to fight. However, Yamamoto’s vociferous arguments against going to war with America were overruled by the High Command. The attack on Pearl Harbor, which was influenced by the successful British attack that used carrier aircraft against the Italian fleet at Taranto, Italy the previous year, was essentially a last best-hope for Japanese success in the Pacific.
Early in the morning on December 7, more than 350 Japanese planes attacked about 33 American ships on orders of Vice-Admiral Chuichi Nagumo. America sustained a loss of nearly 170 aircraft destroyed and 160 damaged that morning, as well as three ships destroyed and 16 damaged. Three thousand seven hundred Americans lost their lives, including 68 civilians. The cost to the Japanese was 29 aircraft, five midget submarines, and 130 service personnel, all but one of whom was killed in action.
The Pearl Harbor Memorial
The Pearl Harbor memorial, otherwise known as the USS Arizona Memorial, is a National Monument located at the site of the sunken battleship USS Arizona in Pearl Harbor. Commemorating the 1,177 crewman who lost their lives in the attack on Pearl Harbor, it s a tribute to World War II valor in the Pacific. Learn more about the Pearl Harbor Memorial.
As a wave of shock surged from Pearl Harbor’s burning waters, the nation stood in awe of the destruction wrought by the Imperial Japanese Navy on the U.S. Pacific Fleet. “The incredulousness of it all still gives each new announcement of the Pearl Harbor attack the unreality of a fairy tale,” a young naval aviator stationed in Virginia wrote just hours after the attack. “How could they have been so mad?… If the reports I’ve heard today are true, the Japanese have performed the impossible, have carried out one of the most daring and successful raids in all history.… The whole thing was brilliant.”
In just 90 minutes, the Japanese had inflicted a devastating blow: five battleships were sunk, three battleships, three cruisers, and three destroyers were damaged, and nearly 200 aircraft were destroyed. The most devastating loss was the 2,403 Americans killed and 1,178 wounded. Michael Slackman, a consulting historian to the U.S. Navy, described the attack as “almost textbook perfect” in his book Target: Pearl Harbor (1990). Gordon Prange, the battle’s leading historian, judged it “brilliantly conceived and meticulously planned.” Another prominent historian, Robert L. O’Connell, author of Sacred Vessels: The Cult of the Battleship and the Rise of the U.S. Navy (1995), likened it to the perfection of a “flashing samurai sword.” Even the recorded narration on a Pearl Harbor tour boat says the attack was “brilliantly conceived and executed.”
Yet a detailed examination of the preparation and execution of the attack on the Pacific Fleet reveals a much different story. Even after 10 months of arduous planning, rehearsal, and intelligence gathering, the attack was plagued by inflexibility, a lack of coordination, and misallocated resources. A plan for a likely contingency was cobbled together by three mid-grade officers while en route to Hawaii. The attack itself suffered significant command blunders. Though armed with enough firepower to destroy up to 14 battleships and aircraft carriers, the Japanese landed killing hits on only three battleships; luck, combined with American damage control mistakes, added two more battleships to their tally. Not only was the Japanese attack on Pearl Harbor far from brilliant, it also narrowly avoided disaster.
High Command and Aviators Disagree on Primary Targets
Admiral Isoroku Yamamoto, commander in chief of Japan’s Combined Fleet, thought he saw a way to win an impossible war, beginning with a surprise attack against American battleships. He believed battleships possessed “intangible political effects internationally as a symbol of naval power.” Sinking them, in tandem with capturing the Philippines, would so shock and demoralize the American people that their will to continue the war would sink along with the shattered battlewagons. The Japanese Naval General Staff wanted to sink battleships, too, but for a different reason: they calculated (from some faulty initial assumptions) that crippling four of the eight battleships in port would prevent the Pacific Fleet from sailing to relieve the Philippines for six months, allowing the Japanese to secure the flank of their southern advance.
The aviators involved had other target priorities. The operation’s main planner, Commander Minoru Genda, was a brilliant and iconoclastic fighter pilot known as “Madman Genda” for his belief that battleships were anachronisms. While a student at the Naval Staff College, he had called for the Imperial Navy to scrap all battleships and build only carriers. When assigned in early 1941 to plan an attack to sink battleships at Pearl Harbor, he instead plotted to aim the bulk of the attack at any carriers that might be in port. His fixation would come close to disrupting the entire attack.
The plan finally presented to the admirals called for a first wave of 40 Nakajima B5N carrier attack bombers (later code-named “Kates” by the Allies), each carrying a Type 91 aerial torpedo, to open the assault on Pearl Harbor. According to the Japanese Official History, they were to first attack four designated battleships, then shift their attention to carriers. After crippling or sinking these ships, the attack would shift to the remaining battleships, then shift again to cruisers.
It was an overly complex, impossible scheme, likely constructed merely to brief the admirals, who were largely ignorant of aviation tactics and would not know that such an orderly progression through the targets was unworkable. Genda and the planners were well aware that the torpedo bombers had to fly low and slow as they approached their targets, making them extremely vulnerable to antiaircraft fire.
The plan they intended to use split 90 Kates between two roles: torpedo and level bombing. Genda then divided the 40 acting as torpedo bombers into four formations. They were to travel together to a point north of Pearl Harbor, where 16 torpedo bombers in two formations would separate to approach from the west and attack the carrier moorings, while 24 torpedo bombers in two formations would attack Battleship Row from the east. Immediately after, 50 more Kates acting as level bombers would attack from high altitude, dropping massive 1,760-pound armor-piercing bombs on the battleships sheltered from torpedo fire by other ships or dry docks.
The plan emphasized surprise; all 40 torpedo bombers could deliver their attacks in less than 90 seconds, before the enemy defenses could respond. It would be impossible for the torpedo bomber aircrews to methodically ratchet through a complicated target prioritization scheme because they would not be in a position to observe or evaluate the attacks of the aircraft that went before them. Each aircrew could only do their best to identify a good target, launch a torpedo, and get out as quickly as possible. They were instructed to concentrate their attacks to ensure that ships would be sunk rather than just damaged, but at the same time avoid “overkill” on ships already sinking, as any such hits would be a waste and better applied to other targets.
A second wave of the attack was to be launched about an hour after the first: 81 Aichi D3A dive-bombers (“Val”) armed with 550-pound general-purpose bombs—which were unable to penetrate battleship deck armor—had the carriers as their primary targets. They were to stay on those targets, even if the carriers had been sunk or capsized by the torpedo bombers.
Genda, true to his philosophy, assigned twice as many torpedo bombers per carrier than per battleship, despite the fact that fewer hits would sink a carrier. In other words, he allocated more than enough firepower to sink the carriers, but sent only enough firepower to cripple the battleships. He wanted to guarantee the carriers would never be salvaged.
Inadequate Rehearsal Sets the Stage for Gaffes
The Imperial Japanese Navy had begun preparing for the Pacific War in earnest in 1938. They grounded their hopes that their smaller navy would prevail through better tactics, better weapons, and better training. Realism, not safety precautions, drove their intensive preparations. Destroyers practiced torpedo attacks at night and in poor weather at high speed, resulting in some catastrophic collisions. Night bombing attacks were practiced while searchlights dazzled the pilots, resulting in midair collisions. The cost in airplanes and lives was deemed acceptable.
Yet the attack on Pearl Harbor went forward without a realistic dress rehearsal. Each mission type—dive-bomber, level bomber, torpedo bomber, and fighter—trained independently. The Japanese simply did not practice combined arms doctrine, which utilizes different types of units in complementary ways to achieve an objective. There was no combined training until the very end, when the Japanese staged two practice attacks against target battleships at anchor in Japan’s Inland Sea, and against a nearby airfield. But the ships were not arrayed as in Pearl Harbor, the sun angle and geography were different, and the approaches were nothing like Oahu’s narrow lochs. The torpedo bombers apparently did not even employ the attack formation they would later use. On top of all that, they repeatedly concentrated on the easiest targets; no corrective action was taken.
Poor Planning Neglects a Likely Contingency
On the eve of their departure, the planners realized that everything they had devised and practiced was based on achieving surprise. What if the Americans were alert?
Genda met with Lieutenant Commander Mitsuo Fuchida, the strike commander, and Lieutenant Shigeharu Murata, the torpedo bomber commander, in the flagship’s wardroom after departing from Japan. They devised a modification to the master plan: Fuchida, leading the first wave, would fire one flare for “surprise achieved” or two flares for “surprise lost.” If the Americans were on the alert, the first-wave dive-bombers—which, in the original plan, were to orbit north of the harbor until the torpedo bombers finished their attack—would surge ahead and bomb Ford Island and Hickam Field to draw antiaircraft fire from the torpedo bombers.
This last-minute change held the spark of chaos. It was formulated without any flag officer or senior staff captain present; Genda and Fuchida were probably embarrassed that they had neglected such an obvious contingency. Murata objected to the plan, unwilling to risk his vulnerable torpedo bombers against an awakened defense, but was overruled. Reflecting the lack of a combined arms approach, the new plan was cemented without input from the fighter or dive-bomber leaders.
Another key contingency emerged at the last minute—and was ignored. The day before the strike, Japanese intelligence reported that there were no carriers in Pearl Harbor. Genda could have redirected the attack to focus on battleships and cruisers. However, a staff officer expressed hope that the carriers might return in the few hours remaining before the attack. Genda brightened: “If that happened, I don’t care if all eight battleships are away.” The plan remained unchanged.
Communications Blunder Distorts Attack Plan
As the first wave neared Oahu’s northern shore just after 7:30 a.m. on December 7, clouds blocked the route down the center of Oahu. Fuchida veered, leading the way down the island’s west side. After the massed formation cleared the clouds, he made no attempt to regain the planned track.
Spotting no sign that their presence had been detected, Fuchida fired a single flare to activate the “surprise” attack plan. When the fighters did not take up their assigned positions, however, he assumed they had missed the signal and fired another—without considering that the observers might take this as the two-flare signal. He groaned as the dive-bomber leader, believing that surprise had been lost, raced ahead of the torpedo bombers to make his diversionary attack.
Fuchida later told Gordon Prange, the author of At Dawn We Slept (1981), that he “ground his teeth in rage [but later] realized that the error made no practical difference.” He also diverted blame onto the dive-bomber leader—“that fool Takahashi, he was a bit soft in the head.”
Fuchida’s blunder did in fact make a monumental practical difference: with half the aviators trying to execute a different plan, order disintegrated as the dive-bombers and torpedo bombers raced each other to the harbor like horses released from the starting gate at the Kentucky Derby. The dive-bombers arrived first, without climbing to standard bombing altitude, which reduced the accuracy of their attacks. Their bombs, exploding on Ford Island and Hickam Field, awoke American defenders aboard ships in the harbor.
Because the attack groups split up west rather than north of the harbor, the torpedo bombers assigned to strike the carrier moorings commenced their attack about five minutes before their counterparts assigned to Battleship Row. This granted still more reaction time for the defenders; on average, around 25 percent of each vessel’s antiaircraft guns were manned and stocked with ammunition as the attack began. As a result, the first torpedo bomber to attack a battleship was met with heavy fire. Most of the torpedo planes were hit, and five of the last seven to arrive were shot down, all due to Fuchida’s mistake.
Torpedo Bomber Formation Errors Result in Chaos
The planners had selected a long single-file attack formation for the torpedo bombers, with 500-meter (7-second) intervals between aircraft, which they believed suited Pearl Harbor’s long, narrow lochs. It proved a poor choice.
In the confusion following Fuchida’s blunder with the flares, and the pilots’ apparent lack of practice in changing from cruise to attack formation, up to 1,800 meters (30 seconds) stretched between aircraft, and miles opened between the two formations that were to attack Battleship Row. Pilots lost sight of their leaders, or even the aircraft ahead, and had to gain altitude and circle to get their bearings. Some broke away from their formation leader and attacked independently. There were mistakes, aborted runs, misidentified targets, and at least one near collision that forced a bomber to jettison its torpedo.
Instead of a tightly timed attack lasting 90 seconds, the torpedo attack stretched out over 11 minutes, with torpedo bombers spaced far apart, allowing the defenders’ antiaircraft fire to concentrate on each in turn.
At this point, Japanese fighters had detached to strafe nearby airfields. Had American fighters been aloft over the harbor, instead of grounded by communication issues, the scattered torpedo bombers could easily have been slaughtered.
With no carriers in port, nearly half the torpedo bombers fell into disarray over which ships to target.
Lieutenant Hirata Matsumara, leading 16 torpedo bombers, struggled to identify targets against the early morning sun’s glare—a challenge the rehearsals had not prepared him for. Impatient aviators surged ahead and Matsumara’s formations disintegrated. Six torpedo bombers misidentified the demilitarized battleship Utah as a frontline battleship and attacked, scoring only two hits. One torpedo missed Utah so badly it hit the light cruiser Raleigh in an adjacent berth. Considering that this first wave was unopposed by enemy fighters and flew the easiest approach—similar to rehearsals, when 83 percent of the torpedo bombers hit their targets—it was a miserable performance.
The remaining 10 bombers in the carrier attack group swung south of Ford Island looking for battleships; none of the aviators wanted to come home from the most important battle in Japanese history to say they had attacked a secondary target. Five misidentified the backlit silhouette of the old minelayer Oglala, moored outboard of the light cruiser Helena, as a battleship; only one torpedo hit. In all, 11 of the 16 torpedoes from the group assigned to attack carriers—more than a quarter of the 40 torpedoes in the entire attack—were launched at misidentified targets.
The Battleship Row attackers made their runs under heavy fire, further hampered by the remaining bombers from Matsumara’s group that were trying to squeeze in their attacks at the same time. All were desperate to drop their torpedoes before the defending antiaircraft fire became more intense and, just as in rehearsals, aimed mostly at the easiest targets—the battleships Oklahoma and West Virginia. Of the 19 total torpedo hits, these two battleships absorbed 12—nearly two-thirds of the hits. Four of these were overkill, wasted torpedoes that would have been more effective against the battleships California, which received only two hits, and Nevada, which received just one.
Only 11 torpedo hits were against properly identified targets that were part of the objective; the score rises to 13 if the accidental hits on the cruisers Raleigh and Helena are included. Thus, at best 33 percent of the torpedoes brought to the battle were effective—far short of the 67 percent Genda had expected.
Just before the 81 second-wave dive-bombers launched, the pilots were informed that the American carriers were not in port. Rather than turning their focus to the secondary targets—cruisers—word was circulated that they were to finish off ships damaged in the first attack. Many of the pilots took this vague declaration as an order to strike battleships, despite the known ineffectiveness of their general-purpose bombs in this role.
While the second wave approached the harbor, Fuchida—after dropping his armor-piercing bomb (a miss)—spent 30 minutes circling the harbor. He could have identified targets for the dive-bombers and directed their attacks. Instead, he did nothing. The most senior aviator over Pearl Harbor was a passive observer.
The dive-bomber pilots, left to select targets, wasted most of their ordnance. Forty percent of the dive-bombers went after battleships. Another 7 dropped their payload on destroyers misidentified as cruisers, 16 attacked auxiliary vessels misidentified as cruisers or battleships, 8 bombed a destroyer in dry dock, 2 attacked an oiler in the channel, and 1 attacked an ammunition ship. One may even have attacked the Dutch liner Jagersfontein in Honolulu Harbor, 10 miles away. Only 14 of the 78 bombers that arrived at Pearl Harbor attacked appropriate targets—cruisers.
The Japanese expected their dive-bombers to land 49 hits, a 60 percent success rate; even with a charitable definition of what constitutes a hit, they achieved only 15 hits, or 19 percent. Three bombs that had been aimed at battleships missed so badly they hit destroyers, so only 15 percent of the bombs actually hit their intended targets—another miserable performance.
Five hits were scored on the battleship Nevada, a ship already sufficiently damaged by a torpedo strike in the first wave. These hits triggered a damage control blunder by the Americans, which ultimately sank the ship. Single hits on California and Pennsylvania caused little damage.
The remaining second-wave dive-bombers contributed nothing to Japan’s objective of immobilizing the Pacific Fleet for six months. There was only one direct hit on a cruiser, Raleigh, but like the Nevada it had already been torpedoed and would be out of the war for six months. A near miss caused some flooding aboard the cruiser Honolulu, quickly repaired. Three hits landed on a destroyer in a floating dry dock. Another hit on an aircraft tender was later mended in a single day at the San Diego shipyard.
Overall, the Japanese attack fell far short of its potential. There were eight battleships and eight cruisers in port; four of each were accessible to torpedo attack. The Japanese had more than enough armor-piercing bombs to sink the ships inaccessible to torpedoes, along with two of the four battleships that were either double-berthed or in dry dock, and enough general-purpose bombs to sink all of the cruisers. But instead of destroying 14 of the 16 priority targets, they dropped killing ordnance on only three: Oklahoma, West Virginia, and Arizona. Two other battleships —California and Nevada—later sank because of flooding, damage control errors, and poor construction. This raised the score to 5 of the 16 priority targets, or only 31 percent—a poorly planned and executed attack, no matter how it is dissected.
Lessons of a Flawed Victory
Its flaws aside, however, the attack’s results are all too familiar. Japan succeeded in taking the United States by surprise. Five battleships sank; the loss of American lives shook the nation to its core. December 7, 1941, will never cease to live in infamy.
But examining the attack’s planning and execution blunders offers a key perspective on the Pacific War. Defeat forces change; victory entrenches the current system, with all its faults.
By celebrating its success at Pearl Harbor, Japan sheltered myriad problems. Victory obscured poor planning, to be seen again at Midway; poor staff procedures were evident later at Guadalcanal. Poor target selection, attack tactics, and accuracy appeared again in the carrier battles; poor aerial command and control manifested throughout the war. Victory perpetuated a samurai approach to aerial combat that led to horrendous losses.
Most significantly, Pearl Harbor cemented the Japanese belief that they could achieve stunning victory against all odds—that with sufficient will and the favor of the gods they could achieve the impossible. This sustained Japan when defeat was inevitable; it prolonged the war; it nurtured the Bushido warrior spirit—and its dark side, the kamikaze. Paradoxically, the Japanese victory at Pearl Harbor firmly entrenched the seeds of the destruction of their navy, and near destruction of their nation.
Alan D. Zimm heads a section of the Aviation Systems and Advanced Concepts Group at the Johns Hopkins University Applied Physics Laboratory. He is a former surface line officer in the U.S. Navy. His book The Attack on Pearl Harbor: Strategy, Combat, Myths, Deception was released in May 2011 by Casemate Publishers.