"I look forward to the day when a free India and a free China will co-operate together in friendship and brotherhood for their own good and for the good of Asia and the world," Mahatma Gandhi wrote in a letter to the Chinese nationalist leader Chiang Kai Shek, who, in 1942, had asked Gandhi to suspend the agitation against Britain and help the Allied forces fight the Japanese in China. Gandhi was reluctant, saying that he couldn't help buy China's freedom at the cost of India's.
Instead Gandhi offered the use of India as a base for Chinese operations against the Japanese.
However, the Mahatma had little bearing on the role of the Indian army under British rule. Indian soldiers fought in Burma and South East Asia to combat Japanese aggression against China, even as Subash Chandra Bose and the Azad Hind Fauj were aligning with Tokyo.
The little known China-Burma-India Theatre, often referred to as "The Forgotten Theater of World War II" was established by the US in 1942 to fight the Japanese in China. India served as the base for these US-led operations. In the clip above we can see the Chinese troops under US General Joseph W Stilwell and Chiang Kai-shek being trained "somewhere in India."
The US interest was largely in keeping the Chinese supplied so that it could continue the war against Japan. With only a couple of supply routes into China remaining – one was from Burma, and another, the treacherous air route from Arunachal Pradesh called "The Hump", a site of many crashes – the focus was on clearing these up first.
The first offensive in Burma didn't go too well, though. The combined forces of British, Indian and Chinese soldiers "got a hell of a beating" from the Japanese in Burma, Stilwell told reporters in May 1942. The clip above is from the time following that defeat in Burma, in preparation of a new offensive.
The Japanese invasion of China had begun long before the World War, in 1931. Japan harboured imperial ambitions and wanted to create a Great East Asia Co‑Prosperity Sphere (A Japanese-dominated new Asian order). By the late 1930s Japan had control over a major part of China. Following a fight over an ornate bridge, the Lugouqiao, near Beijing, disparate Chinese leaders finally came together to declare a full-blown war against Japan. Starting in 1937, the long and bloody battle came to an end after eight years, in 1945.