pibindia.wordpress.com/2017/04/08/hundred-years-of-champaran-satyagraha
The Champaran Satyagraha of 1917 was the first Satyagraha movement led by Gandhi in India and is considered a historically important revolt in the Indian Independence Movement. It was a farmer's uprising that took place in Champaran district of Bihar, India, during the British colonial period. The farmers were protesting against having to grow indigo with barely any payment for it.
When Gandhi returned to India from South Africa in 1915, and saw peasants in northern India oppressed by indigo planters, he tried to use the same methods that he had used in South Africa to organize mass uprisings by people to protest against injustice.
Champaran Satyagraha was the first popular satyagraha movement. The Champaran Satyagraha gave direction to India's youth and freedom struggle, which was tottering between moderates who prescribed Indian participation within the British colonial system, and the extremists from Bengal who advocated the use of violent methods to topple the British colonialists in India
Source: en.wikipedia.org/wiki/Champaran_Satyagraha