When and where was the first major agitation led by Gandhi, tell me who this agitation was against,  which crop led to this agitation and why this agitation happened.

Context: Gandhi's first major achievement came in 1917 with the Champaran agitation in Bihar. The Champaran agitation pitted the local peasantry against largely Anglo-Indian plantation owners who were backed by the local administration. The peasants were forced to grow indigo, a cash crop for Indigo dye whose demand had been declining over two decades, and were forced to sell their crops to the planters at a fixed price. Unhappy with this, the peasantry appealed to Gandhi at his ashram in Ahmedabad. Pursuing a strategy of nonviolent protest, Gandhi took the administration by surprise and won concessions from the authorities.

Answer: First major agitation was in 1917 in Champaran Bihar state. The agitation was against Anglo-Indian plantation owners. Indigo was the crop that led to this agitation and the reason was the lower fixed price for the Indigo crop.