The peasants of Champaran and other areas of North Bihar were growing indigo under the Tinkathia system. Under this system, the peasants were bound to plant 3 out of 20 parts of land with indigo for the landlord.
This means that out of 20 khatas which make an acre, they had to dedicate 3 khatas for indigo plantation leaving peasants in extreme poverty.
Mahatma Gandhi was invited by some of the peasants to look after their misery. Gandhiji accepted the invitation and started a mass movement.
Gandhiji established an ashram here and handpicked eminent lawyers like Dr. Rajendra Prasad to study the atrocities on the villagers and worked for the betterment of the villages. This was the first time Gandhi used the word Satyagraha.
As a result, Gandhiji was arrested and was asked to leave the province for creating unrest. Finally, a law was passed exempting farmers from Indigo plantation.
It was during this agitation he was called Bapu and Mahatma for the first time.