Why didn't Gandhi believe in the use of force to overthrow the British?

Gandhi took the religious principle of ahimsa which means doing no harm, common to Buddhism, Hinduism and Jainism and turned it into a non-violent tool for mass action. He used it to fight not only colonial rule but social evils such as racial discrimination and untouchability as well.

on april 6, 1917, the u.s. joined its allies--britain, france, and russia--to fight in world war i. under the command of major general john j. pershing, more than 2 million u.s. soldiers fought on battlefields in france.