Champaran (Bihar) — Mahatma Gandhi organised Satyagraha here in 1917 to inspire peasants to struggle against the oppressive indigo plantation system.
Source: Chapter 2, Section 1.1 – The Idea of Satyagraha
For map-skill questions asking to identify a place, name the location clearly and add one supporting fact (what happened there). Examiners expect "Champaran" as the answer; mentioning Bihar and the indigo/plantation context confirms you know the historical context, which secures full marks.