Monday, April 6, 1942. The Japanese strike India.

From Sarah Sundin's excellent day-to-day history of World War Two blog:

Today in World War II History—April 6, 1942: 80 Years Ago—Apr. 6, 1942: Japanese air raid on Vizagapatam and Cocanada, India, helps tip India to support the Allies. Germany cuts ration of bread, meat, and fats. Due to heavy Luftwaffe raids, British Royal Navy begins to withdraw surface ships from Malta to Gibraltar and Alexandria. Seven hundred Japanese-Americans are assembled at Santa Anita Racetrack. First group of Japanese-Americans are evacuated from San Francisco.

I'd draw attention to the first one of these items in particular. 

The British were trying to secure the support of India which, while it remained part of the British Empire, was increasingly moving towards independence and achieving it by default.  It would end up, however, contributing an army to the Allies which was the largest in the war, in terms of sheer manpower.

India had of course contributed manpower in the form of the Indian Army to the British Empire in World War One. But, like other parts of the Empire, it was increasingly reluctant to become as engaged in World War Two, and unlike Canada, Australia and New Zealand (as well as Ireland, which remained neutral in the war) it was not a self-governing dominion with de facto independence.  Indeed, in spite of ultimately fully committing to the Allied cause, a substantial number of Indians would end up in a rebel Indian army that served under the Japanese, although not terribly effectively.

The Japanese strike fit into a series of actions which caused people who remained subject to colonial rule in Asia to reject the Japanese as worse rulers, for the most part, than the Europeans had been, with Indonesia, where the Japanese were generally preferred, being the exception.  

The war ultimately accelerated the demise of colonialism, which was exposed as too hypocritical in light of Allied war aims, let alone propaganda, and the arming of local forces made it effectively impossible to keep on in the former role after the war.  A major impact of the war, therefore, was to complete the global death of empire, even if they'd linger on in various locations for decades.