The chapter highlights the transformation of the Indian National Movement into a mass movement led by Mahatma Gandhi, emphasizing key events and movements from 1915 to 1947. It explores various phases, including the Non-Cooperation Movement, Civil Disobedience Movement, and Quit India Movement, each marked by significant participation and events. The formation of the Indian National Congress and the impact of World War II are also discussed, culminating in the transfer of power and the partition of India.