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Pearl Harbor Timeline

(December 7, 1941)

The attack on Pearl Harbor was a surprise military strike by the Imperial Japanese Navy against the United States naval base at Pearl Harbor, Hawaii, on December 7, 1941. The attack killed over 2,400 Americans, damaged or destroyed numerous ships and aircraft, and led directly to the United States declaring war on Japan and entering World War II. Less

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Rising Tensions

Early Japanese arguments for taking Hawaii

1924

As early as 1924, and again in 1932, Admiral Seijiro Kawashima and Commander Hironori Mizuno argued that in any war with the United States, Japan needed to take Hawaii, warning that failure to do so would doom the war to being prolonged and prevent Japan from winning.

US Air Service survey of Pacific vulnerabilities

1924

Chief of United States Air Service Mason Patrick showed concern for military vulnerabilities in the Pacific, sending General Billy Mitchell on a survey of the Pacific and the East to assess American defenses.

Japan invades Manchuria

1931

Tensions between Japan and the United States did not seriously grow until Japan's invasion of Manchuria in 1931, which marked the beginning of Japanese expansionism that would eventually bring the two nations into conflict.

Image source: Japanese invasion of Manchuria

Japan invades Manchuria

Naval war game proves Pearl Harbor vulnerable

1932

At least two naval war games, one in 1932 and another in 1936, proved that Pearl Harbor was vulnerable to a surprise carrier-based air attack, yet warnings went largely unheeded.

Memorandum by Stanley K. Hornbeck

Oct 24, 1934

In a memorandum dated October 24, 1934, Chief of the Division of Far Eastern Affairs Stanley K. Hornbeck addressed growing concerns over Japanese ambitions in the Pacific.

Second Sino-Japanese War begins

1937

Over the decade following the invasion of Manchuria, Japan expanded into China, leading to the outbreak of the Second Sino-Japanese War in 1937 and further straining relations with Western powers.

Image source: Second Sino-Japanese War

Second Sino-Japanese War begins

USS Panay attack and Rape of Nanjing turn opinion against Japan

Dec 1937

Starting in December 1937, events such as the Japanese attack on USS Panay, the Allison incident, and the Rape of Nanjing swung Western public opinion sharply against Japan.

Image source: USS Panay incident

USS Panay attack and Rape of Nanjing turn opinion against Japan

American companies stop supplying Japan with war implements

1938

In 1938, following an appeal by President Roosevelt, American companies stopped providing Japan with implements of war, an early step in economic pressure against Japanese expansionism.

United Kingdom at war with Germany

Sep 1939

The United Kingdom had already been at war with Germany since September 1939 and with Italy since June 1940, and British prime minister Winston Churchill had promised to declare war 'within the hour' of a Japanese attack on the United States.

US adopts Plan Dog strategy

1940

Unknown to Yamamoto, the US Navy had decided as far back as 1935 to abandon charging across the Pacific towards the Philippines in response to war, and instead adopted Plan Dog in 1940, emphasizing keeping the Imperial Japanese Navy out of the eastern Pacific while concentrating on defeating Nazi Germany.

Japan invades French Indochina

1940

In 1940, Japan invaded French Indochina, attempting to stymie the flow of supplies reaching China, an action that further provoked the United States.

Image source: Japanese invasion of French Indochina

Japan invades French Indochina

Pacific Fleet based at Pearl Harbor

1940

In 1940, the US Pacific Fleet was based at Pearl Harbor, making it a target for Isoroku Yamamoto's planned pre-emptive strike intended to prevent it from interfering with Japan's planned actions in Southeast Asia.

Japan-US negotiations during 1941

1941

Japan and the United States engaged in negotiations during 1941, attempting to improve relations, but the talks ultimately failed to resolve the deepening crisis.

US ceases oil exports to Japan

Jul 1941

The United States finally ceased oil exports to Japan in July 1941, following the seizure of French Indochina after the Fall of France, in part because of new American restrictions on domestic oil consumption.

Observers expect imminent hostilities

Nov 1941

By late 1941, many observers believed that hostilities between the United States and Japan were imminent, though few anticipated a strike on Pearl Harbor itself.

Image source: Attack on Pearl Harbor

Observers expect imminent hostilities

Hull note delivered to Japan

Nov 26, 1941

Japan dispatched its naval attack group on November 26, 1941, just before receiving the Hull note, which stated the US desire that Japan withdraw from China and French Indochina.

Image source: Hull note

Hull note delivered to Japan

Planning the Attack

Preliminary planning for Pearl Harbor attack begins

Jan 1941

Preliminary planning for an attack on Pearl Harbor to protect the move into the Southern Resource Area, the Japanese term for the Dutch East Indies and Southeast Asia generally, began early in 1941 under Admiral Isoroku Yamamoto, commander of the Combined Fleet.

Planners study British attack on Taranto

1941

The planners studied the 1940 British air attack on the Italian fleet at Taranto intensively, drawing lessons for a carrier-based aerial assault on battleships at anchor.

Image source: Battle of Taranto

Planners study British attack on Taranto

Full-scale planning underway for the attack

Mar 1941

By early spring 1941, full-scale planning was underway, primarily by Rear Admiral Ryūnosuke Kusaka, with assistance from Commander Minoru Genda and Yamamoto's Deputy Chief of Staff, Captain Kameto Kuroshima.

War games discussion: invasion of Hawaii rejected

Sep 5, 1941 - Sep 17, 1941

In the wake of discussions following the war games drilling for the Pearl Harbor attack on September 5–17, 1941, Admiral Isoroku Yamamoto ultimately decided against attempting an invasion of Hawaii.

Five I-boats depart Kure Naval District

Nov 25, 1941

The five I-boats, midget submarines intended to penetrate Pearl Harbor, left Kure Naval District on November 25, 1941, as part of the operation.

Kido Butai departs Hittokapu Bay

Nov 26, 1941

On November 26, 1941, Kido Butai, the Mobile Strike Force of the Japanese Navy, departed Hittokapu Bay on Etorofu Island in the Kuril Islands: six aircraft carriers (Akagi, Kaga, Sōryū, Hiryū, Shōkaku, and Zuikaku), two battleships, three cruisers, 11 destroyers, and eight oilers.

The Attack

Battleship losses at Pearl Harbor

Dec 7, 1941

Oklahoma was hit by five torpedoes and capsized; West Virginia was sunk by two bombs and seven torpedoes; California was sunk; Nevada was beached; and Tennessee and Maryland were each hit by two bombs, among the heavy damage inflicted on the fleet.

Casualties of the attack

Dec 7, 1941

2,008 sailors were killed and 710 others wounded; 218 soldiers and airmen were killed and 364 wounded; 109 Marines were killed and 69 wounded; and 68 civilians were killed and 35 wounded. The attack remains the deadliest non-pathological disaster in Hawaii's history.

First-wave bombing of Battleship Row

Dec 7, 1941

In the first-wave attack, about eight of the forty-nine 800-kg armor-piercing bombs dropped hit their intended battleship targets, inflicting devastating damage on the American fleet.

Attack on Pearl Harbor

Dec 7, 1941

The Attack on Pearl Harbor was a surprise military attack by the Empire of Japan on the US Pacific Fleet at its naval base at Pearl Harbor in Oahu, Hawaii, on December 7, 1941, leading Roosevelt to famously label it 'a date which will live in infamy'.

Tokyo transmits the 14-Part Message

Dec 7, 1941

Tokyo transmitted the 5000-word notification, commonly called the 14-Part Message, in two blocks to the Japanese Embassy in Washington, intended to break off negotiations before the attack began.

Aftermath and Legacy

Japan begins the Philippines campaign

Dec 8, 1941

Japan began the Philippines campaign hours after Pearl Harbor (because of the time difference, it was December 8 in the Philippines), launching its broader offensive across Southeast Asia.

Image source: Philippines campaign (1941–1942)

Japan begins the Philippines campaign

Canada orders removal of Japanese Canadians

Feb 24, 1942

On February 24, 1942, Order-in-Council P.C. 1486 was issued under the War Measures Act, allowing for the forced removal of any and all Canadians of Japanese descent from British Columbia and prohibiting them from returning to the province.

Image source: Internment of Japanese Canadians

Canada orders removal of Japanese Canadians

Battle of Midway scuttles Japan's Hawaii plans

Jun 1942

Japan still harbored plans related to Hawaii after Pearl Harbor, but its decisive defeat at the Battle of Midway in June 1942 permanently scuttled those plans.

Image source: Battle of Midway

Battle of Midway scuttles Japan's Hawaii plans

Wounded receive Purple Hearts

Jun 13, 1944

The wounded later received Purple Hearts, originally reserved for service members wounded by enemy action while partaking in armed conflicts, for their peacetime actions that day on June 13, 1944.

Oklahoma capsizes under tow

May 1947

Oklahoma, while raised, was never repaired and capsized while under tow to the mainland in 1947, having been declared a total loss after the attack.

Image source: USS Oklahoma (BB-37)

Oklahoma capsizes under tow

Midget submarine wreck found outside harbor

1960

One of the Japanese midget submarines involved in the attack was found outside the harbor in 1960, providing physical evidence of the submarine component of the operation.

Firefighters posthumously awarded Purple Hearts

Dec 7, 1984

The three firefighters killed in the attack did not receive their Purple Hearts until December 7, 1984, on the 43rd anniversary of the attack.

Fifth midget submarine wreck discovered

1992 - 2001

In 1992, 2000, and 2001, Hawaii Undersea Research Laboratory's submersibles found the wreck of the fifth midget submarine lying in three parts outside Pearl Harbor.

Key Facts

  1. The attack began at 7:48 a.m. Hawaiian time on Sunday, December 7, 1941, catching American forces largely unprepared.
  2. More than 2,400 Americans were killed, including 1,177 crew members aboard the USS Arizona, which exploded and sank during the attack.
  3. Japan launched 353 aircraft in two waves from six aircraft carriers, targeting battleships, airfields, and other military installations.
  4. Twenty-one American ships were sunk or damaged, and 188 aircraft were destroyed, though key fuel depots and repair facilities survived.
  5. President Franklin D. Roosevelt called December 7 'a date which will live in infamy,' and Congress declared war on Japan the next day, bringing the U.S. into World War II.

Source

This Pearl Harbor timeline was generated with the help of AI, using information found on the internet.

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