Many Indian soldiers flocked to participate in World War I. It was for them Gandhiji extended his support. This was partly due to the promise of the British government to reciprocate by supporting the Indian dream of Swaraj, after the end of World War I.
The largely relocated Indian soldiers fought along with British soldiers. They struggled in numerous areas like Mesopotamia and Europe. Many lost their lives in the battles.
Britain and her allies emerged victorious. But Indians lost their hearts as the British retreated from their promise of self-government after World War I. Instead of self-government, they offered minor reforms, but most of them were disappointing to Gandhiji and his followers. In short, Indians felt embittered.
Then, it became clearer to Gandhiji and his men that the British would not free India, at any cost.