1941 Japanese attack on Pearl Harbour
Context: Japanese-American relations
- relatively friendly since the early 20th century
- marked by agreements like the 1908 Root-Takahira Agreement
- tensions escalated with Japanese expansionism, especially 1931 Japanese invasion of Manchuria
- Japan’s imperial ambitions sought SE Asia's rich resources → clashed with U.S. strategic interest in the region
- ref. 📜 Southern Expansion Doctrine
Timeline
- 1940: U.S. places an embargo on Japan
- 1941 July: Japan expanded territories and occupied French Indochina → U.S. froze all Japanese assets, imposed crippling oil embargo
- Japan was reliant on U.S. oil → this placed Japan under huge pressure
- 1941 September-November: Japan and the U.S. try to negotiate diplomatically
- significant differences in stances resulted in little headway
- 1941 December 7: Japan attacks Pearl Harbour
Factors leading to Pearl Harbour
Impact of War: 1937-1945 Second Sino-Japanese War > 1940-1941 Japanese invasion of French Indochina
1940-1941 Japanese invasion of French Indochina
1940-1941 Japanese invasion of French Indochina
Importan
Resulted in the 1940-1941 U.S. embargo on Japan
- Japan occupied China’s ports, but supplies continued to reach the Chinese government through Chongqing
- some were sent by the Soviets, U.S., and Britain through Burma and China's far western provinces
- majority came through French Indochina, Laos and Cambodia
- Germany’s 1940 defeat of France → its colonies were vulnerable
- Japan requested the French governor of Indochina to occupy its northern regions to cut supply lines to China; in exchange, Japan would allow the Vichy French government to remain
- veiled threat understood, permission granted
- 1940 September: Japan landed troops at Haiphong in French Indochina and soon built airbases
- 1940 September: 3 days after Japan took over, U.S. responds
- prohibited sale of scrap iron and steel Japan; beginning of 1940-1941 U.S. embargo on Japan
- the U.S. was one of Japan’s main suppliers for industry
- increased financial aid to China’s government
- 1941 July: Japan occupied the rest of French Indochina
- page 88 of move to global war andy dailey
Success or fail?
Link to original
- ultimately, a success – supply lines to China were difficult to maintain because of increasing Japanese pressure
Strategic/Military
- neutralise U.S. threat – a significant threat to Japan’s expansionism
- a surprise attack would weaken the U.S. and give it a free hand in Asia, even if only temporarily
- gaining time – consolidating Asian territories and forming a defensive perimeter before the U.S. could mount a counter-offensive
Political
- show of strength – Japan sought to highlight its miltary prowess &
Impact of Pearl Harbour
- Germany and Italy declared war on the U.S. → U.S. entrance into the war
- Japan won the battle, but lost their objective to destroy all three U.S. aircraft carriers which were Not Present
- oil- and torpedo-storage facilities also survived the attack
Casualties
- American
- damaged 4 battleships, sank 4 battleships
- severely damaged/sank 3 cruisers, 3 destroyers, 2 other naval vessels
- destroyed 188 aircraft
- killed over 2400 people, injured 1200 others
- Japanese minimal losses
- 20 aircraft destroyed
- 5 small submarines sunk
- 65 men killed
Sources
- ‘Towards World War: Tripartite Pact to Pearl Harbor (3.1.6) | IB History HL’. TutorChase, https://www.tutorchase.com//notes/ib/history/3-1-6-towards-world-war%3A-tripartite-pact-to-pearl-harbor. Accessed 16 Sep. 2025.