At the time of the Second World War (1939–1945), India was being controlled by the United Kingdom, with the British holding territories in India including over 5 hundred autonomous Princely States; British India officially declared war on Nazi Germany in September 1939. The British Raj, as part of the Allied Nations, sent over two and a half million volunteer soldiers to fight under British command against the Axis powers. Additionally, several Indian Princely States provided large donations to support the Allied campaign during the War. India also provided the base for American operations in support of China in the China Burma India Theatre.
Indian infantrymen of the 7th Rajput Regiment about to go on patrol on the Arakan front in Burma, 1944.
Indians fought with distinction throughout the world, including in the European theatre against Germany, in North Africa against Germany and Italy, in the South Asian region defending India against the Japanese and fighting the Japanese in Burma. Indians also aided in liberating British colonies such as Singapore and Hong Kong after the Japanese surrender in August 1945. Over 87,000 Indian soldiers (including those from modern-day Pakistan, Nepal, and Bangladesh) died in World War II.
The Indian National Congress, led by Mohandas Karamchand Gandhi, Sardar Vallabhbhai Patel and Maulana Azad, denounced Nazi Germany but would not fight it or anyone else until India was independent. Congress launched the Quit India Movement in August 1942, refusing to co-operate in any way with the government until independence was granted. The government was ready for this move. It immediately arrested over 60,000 national and local Congress leaders and then moved to suppress the violent reaction of Congress supporters. Key leaders were kept in prison until June 1945, although Gandhi was released in May 1944 because of his health. Congress, with its leaders incommunicado, played little role on the home front. The Muslim League rejected the Quit India movement and worked closely with the Raj authorities.
Subhas Chandra Bose (also called Netaji) broke with Congress and tried to form a military alliance with Germany or Japan to gain independence. Japan helped him set up the Indian National Army (INA) which fought under Japanese direction, mostly in Burma. Bose also headed the Provisional Government of Free India, a government-in-exile based in Singapore. It controlled no Indian territory and was used only to raise troops for Japan.
By 1942, neighbouring Burma was invaded by Japan, which by then had already captured the Indian territory of Andaman and Nicobar Islands. Japan gave nominal control of the islands to the Provisional Government of Free India on 21 October 1943, and in the following March, the Indian National Army with the help of Japan crossed into India and advanced as far as Kohima in Nagaland. This advance on the mainland of South Asia reached its farthest point on India territory, retreating from the Battle of Kohima in June and from that of Imphal on 3 July 1944.