Malayan campaign in the context of "French Indochina in World War II"

The Pacific War, sometimes called the Asia–Pacific War or the Pacific Theater, was the theater of World War II fought between the Japan and the Allies in East and Southeast Asia, the Pacific and Indian Oceans, and Oceania. It was geographically the largest theater of the war, including the Pacific Ocean theater, the South West Pacific theater, the Second Sino-Japanese War, and the brief Soviet–Japanese War, and included some of the largest naval battles in history. War between Japan and the Republic of China had begun in 1937, with hostilities dating back to Japan's invasion of Manchuria in 1931, but the Pacific War is more widely accepted to have begun in 1941, when the United States and United Kingdom were brought into the war, after being attacked by Japan.

Japan invaded French Indochina in 1940, and extended its control over the entire territory in July 1941. On 7–8 December 1941, Japan attacked the American naval base at Pearl Harbor in Hawaii; the U.S.-held Philippines, Guam, and Wake Island; and the British colonies of Malaya, Singapore, and Hong Kong, followed by a Japanese declaration of war. The Japanese achieved great success over the next 6 months, allying with Thailand and capturing the listed territories (except for Hawaii) in addition to Borneo, New Britain, the Dutch East Indies, Burma, the Solomon and Gilbert Islands, and parts of New Guinea. In May 1942, Japanese and Allied aircraft carriers fought at the Battle of Coral Sea, resulting in the retreat of a Japanese invasion force headed for Port Moresby. In June, Japan invaded the Aleutian Islands, and in the central Pacific was defeated at the Battle of Midway, considered a key turning point in the war. After this point, the Japanese experienced great difficulty replacing their losses in ships and aircraft as the U.S. produced ever increasing numbers of both.

Lieutenant-General Arthur Ernest Percival, CB, DSO & Bar, OBE, MC, DL (26 December 1887 – 31 January 1966) was a British Army officer. He saw service in the First World War and built a successful military career during the interwar period, but is best known for his defeat in the Second World War, when Percival commanded British Commonwealth forces during the Malayan campaign, which culminated in a catastrophic defeat at the Battle of Singapore.

Percival's surrender to the invading Imperial Japanese Army, which was the largest of its kind in British military history, significantly undermined Britain's prestige and military position in East Asia. Some historians, such as Sir John Smyth, have argued that under-funding of British Malaya's defences and the inexperienced, under-equipped nature of the Commonwealth forces in Malaya, not Percival's leadership, were ultimately to blame for the defeat.

Singapore was captured from the British by the Empire of Japan in February 1942. The Battle of Singapore took place in the South–East Asian theatre of the Pacific War, with fighting lasting from 8 to 15 February 1942. Singapore was the foremost British military base and economic port in South–East Asia and had been of great importance to British interwar defence strategy. The capture of Singapore was therefore a major loss for Britain and resulted in its largest surrender in history.

Before the battle, Japanese General Tomoyuki Yamashita had advanced with approximately 30,000 men down the Malayan Peninsula in the Malayan campaign. The British erroneously considered the jungle terrain impassable, leading to a swift Japanese advance as Allied defences were quickly outflanked. The British Lieutenant-General, Arthur Percival, commanded 85,000 Allied troops at Singapore, although many units were under-strength and most units lacked experience. The British outnumbered the Japanese but much of the water for the island was drawn from reservoirs on the mainland. The British destroyed the causeway, forcing the Japanese into an improvised crossing of the Johore Strait. Singapore was considered so important that Prime Minister Winston Churchill ordered Percival to fight to the last man.

In mid-1940, Nazi Germany rapidly defeated the French Third Republic, and the colonial administration of French Indochina (modern-day Vietnam, Laos and Cambodia) passed to the French State (Vichy France). Many concessions were granted to the Empire of Japan, such as the use of ports, airfields, and railroads. Japanese troops first entered parts of Indochina in September 1940, and by July 1941 Japan had extended its control over the whole of French Indochina. The United States, concerned by Japanese expansion, started putting embargoes on exports of steel and oil to Japan from July 1940. The desire to escape these embargoes and to become self-sufficient in resources ultimately contributed to Japan's decision to attack on December 7, 1941, the British Empire (in Hong Kong and Malaya) and simultaneously the United States (in the Philippines and at Pearl Harbor, Hawaii). This led to the United States declaring war against Japan on December 8, 1941. The United States then joined the side of the British Empire, at war with Germany since 1939, and its existing allies in the fight against the Axis powers.

Indochinese communists had set up a covert headquarters in Cao Bằng Province in 1941, but most of the Vietnamese resistance to Japan, France, or both, including both communist and non-communist groups, remained based over the border, in China. As part of their opposition to Japanese expansion, the Chinese had fostered the formation of a Vietnamese nationalist resistance movement, the Dong Minh Hoi (DMH), in Nanking in 1935/1936; this included communists, but was not controlled by them. This did not provide the desired results, so the Chinese Communist Party sent Ho Chi Minh to Vietnam in 1941 to lead an underground centered on the communist Viet Minh. Ho was the senior Comintern agent in Southeast Asia, and was in China as an advisor to the Chinese communist armed forces. This mission was assisted by European intelligence agencies, and later the US Office of Strategic Services (OSS). Free French intelligence also tried to affect developments in the Vichy-Japanese collaboration.

The Pacific War, sometimes called the Asia–Pacific War or the Pacific Theater, was the theater of World War II fought between Japan and the Allies in East and Southeast Asia, the Pacific and Indian Oceans, and Oceania. It was geographically the largest theater of the war, including the Pacific Ocean theater, the South West Pacific theater, the Second Sino-Japanese War, and the brief Soviet–Japanese War, and included some of the largest naval battles in history. War between Japan and the Republic of China had begun in 1937, with hostilities dating back to Japan's invasion of Manchuria in 1931, but the Pacific War is more widely accepted to have begun in 1941, when the United States and United Kingdom were brought into the war, after being attacked by Japan.

Japan invaded French Indochina in 1940, and extended its control over the entire territory in July 1941. On 7–8 December 1941, Japan attacked the American naval base at Pearl Harbor in Hawaii; the U.S.-held Philippines, Guam, and Wake Island; and the British colonies of Malaya, Singapore, and Hong Kong, followed by a Japanese declaration of war. The Japanese achieved great success over the next 6 months, allying with Thailand and capturing the listed territories (except for Hawaii) in addition to Borneo, New Britain, the Dutch East Indies, Burma, the Solomon and Gilbert Islands, and parts of New Guinea. In May 1942, Japanese and Allied aircraft carriers fought at the Battle of Coral Sea, resulting in the retreat of a Japanese invasion force headed for Port Moresby. In June, Japan invaded the Aleutian Islands, and in the central Pacific was defeated at the Battle of Midway, considered a key turning point in the war. After this point, the Japanese experienced great difficulty replacing their losses in ships and aircraft as the U.S. produced ever increasing numbers of both.

The Imperial edict of declaration of war by the Empire of Japan on the United States and the British Empire (Kyūjitai: 米國及英國ニ對スル宣戰ノ詔書) was published on 8 December 1941 (Japan time; 7 December in the US), 7.5 hours after Japanese forces attacked the United States at Pearl Harbor and British forces in Malaya, Singapore, and Hong Kong. The declaration of war was printed on the front page of all Japanese newspapers' evening editions on December 8. The document was subsequently printed again on the eighth day of each month throughout the war (until Japan surrendered in 1945), to re-affirm the resolve for the war.