South-East Asian theatre of World War II in the context of "Battle of Singapore"

The history of the island of Taiwan dates back tens of thousands of years to the earliest known evidence of human habitation. The sudden appearance of a culture based on agriculture around 3000 BC is believed to reflect the arrival of the ancestors of today's Taiwanese indigenous peoples. People from China gradually came into contact with Taiwan by the time of the Yuan dynasty (1271–1368) and Han Chinese people started settling there by the early 17th century. The island became known by the West when Portuguese explorers discovered it in the 16th century and named it Formosa. Between 1624 and 1662, the south of the island was colonized by the Dutch headquartered in Zeelandia in present-day Anping, Tainan whilst the Spanish built an outpost in the north, which lasted until 1642 when the Spanish fortress in Keelung was seized by the Dutch. These European settlements were followed by an influx of Hoklo and Hakka immigrants from Fujian and Guangdong.

In 1662, Koxinga defeated the Dutch and established a base of operations on the island. His descendants were defeated by the Qing dynasty in 1683 and their territory in Taiwan was annexed by the Qing dynasty. Over two centuries of Qing rule, Taiwan's population increased by over two million and became majority Han Chinese due to illegal cross-strait migrations from mainland China and encroachment on Taiwanese indigenous territory. Due to the continued expansion of Chinese settlements, Qing-governed territory eventually encompassed the entire western plains and the northeast. This process accelerated in the later stages of Qing rule when settler colonization of Taiwan was actively encouraged. The Qing ceded Taiwan and Penghu to Japan after losing the First Sino-Japanese War in 1895. Taiwan experienced industrial growth and became a productive rice- and sugar-exporting Japanese colony. During the Second Sino-Japanese War it served as a base for invasions of China, and later Southeast Asia and the Pacific during World War II.

The Burma campaign in the South-East Asian theatre of World War II was fought primarily by British Commonwealth, China and United States forces against the forces of Imperial Japan, who were assisted by the Burmese National Army, the Indian National Army, and to some degree by Thailand. The British Commonwealth land forces were drawn primarily from the United Kingdom, British India and Africa.

Partly because monsoon rains made effective campaigning possible only for about half of the year, the Burma campaign was almost the longest campaign of the war. During the campaigning season of 1942, the Japanese had conquered Burma, driving British, Indian and Chinese forces from the country and forcing the British administration to flee into India. After scoring some defensive successes during 1943, they then attempted to forestall Allied offensives in 1944 by launching an invasion of India (Operation U-Go). This failed with disastrous losses.

The bombing of Singapore was an attack on 8 December 1941 by seventeen G3M Nell bombers of Mihoro Air Group (Mihoro Kaigun Kōkūtai), Imperial Japanese Navy, flying from Thu Dau Mot in southern Indochina. The attack began at around 0430, shortly after Japanese forces landed on Kota Bharu, Kelantan in northern Malaya. It was the first knowledge the Singapore population had that war had broken out in the Far East.

The Burma campaign was a series of battles fought in the British colony of Burma as part of the South-East Asian theatre of World War II. It primarily involved forces of the Allies (mainly from the British Empire and the Republic of China, with support from the United States) against the invading forces of the Empire of Japan. Imperial Japan was supported by the Thai Phayap Army, as well as two collaborationist independence movements and armies, The State of Burma and the Provisional Government of Free India. Nominally independent puppet states were established in the conquered areas and some territories were annexed by Thailand. In 1942 and 1943, the international Allied force in British India launched several failed offensives to retake lost territories. Fighting intensified in 1944, and British Empire forces peaked at around 1 million land and air forces. These forces were drawn primarily from British India, with British Army forces (equivalent to eight regular infantry divisions and six tank regiments), 100,000 East and West African colonial troops, and smaller numbers of land and air forces from several other Dominions and Colonies. These additional forces allowed the Allied recapture of Burma in 1945.

The campaign had a number of notable features. The geographical characteristics of the region meant that weather, disease and terrain had a major effect on operations. The lack of transport infrastructure placed an emphasis on military engineering and air transport to move and supply troops, and evacuate wounded. The campaign was also politically complex, with the British, the United States and the Chinese all having different strategic priorities. It was also the only land campaign by the Western Allies in the Pacific Theatre which proceeded continuously from the start of hostilities to the end of the war. This was due to its geographical location. By extending from South East Asia to India, its area included some lands which the British lost at the outset of the war, but also included areas of India wherein the Japanese advance was eventually stopped. The climate of the region is dominated by the seasonal monsoon rains, which allowed effective campaigning for only just over half of each year. This, together with other factors such as famine and disorder in British India and the priority given by the Allies to the defeat of Nazi Germany, prolonged the campaign and divided it into four phases: the Japanese invasion, which led to the expulsion of British, Indian and Chinese forces in 1942; failed attempts by the Allies to mount offensives into Burma, from late 1942 to early 1944; the 1944 Japanese invasion of India, which ultimately failed following the battles of Imphal and Kohima; and finally the successful Allied offensive which liberated Burma from late 1944 to mid-1945.

South East Asia Command (SEAC) was the body set up to be in overall charge of Allied operations in the South-East Asian Theatre during the Second World War.

China Burma India Theater (CBI) was the United States military designation during World War II for the China and Southeast Asian or India–Burma (IBT) theaters. Operational command of Allied forces (including U.S. forces) in the CBI was officially the responsibility of the Supreme Commanders for South East Asia or China. In practice, U.S. forces were usually overseen by General Joseph Stilwell, the Deputy Allied Commander in China; the term "CBI" was significant in logistical, material, and personnel matters; it was and is commonly used within the US for these theaters.

U.S. and Chinese fighting forces in the CBI included the Chinese Expeditionary Force, the Flying Tigers, transport and bomber units flying the Hump, including the Tenth Air Force, the 1st Air Commando Group, the engineers who built the Ledo Road, the 5307th Composite Unit (Provisional), popularly known as "Merrill's Marauders", and the 5332d Brigade, Provisional or 'Mars Task Force', which assumed the Marauders' mission.