Background:
The non-cooperation movement was launched by Mahatma Gandhi in 1920 as a peaceful protest against British colonial rule in India.

Causes:
1. The Jallianwala Bagh massacre in 1919, where British troops killed hundreds of unarmed Indian civilians, fueled widespread anger and resentment towards British rule.
2. Indians were disillusioned by the failure of the Montagu-Chelmsford Reforms to grant significant political concessions to Indians.

Key Events:
1. The movement officially began on August 1, 1920, with the issuance of the Non-Cooperation Resolution by the Indian National Congress.
2. Indians were urged to boycott British institutions, courts, schools, and products as a form of nonviolent resistance.
3. Mass protests and demonstrations were organized across the country, with millions of Indians participating in civil disobedience.

Impact:
1. The non-cooperation movement marked a significant shift in the Indian freedom struggle from petitions and protests to mass civil disobedience.
2. The movement garnered widespread support from all sections of society, including peasants, workers, and students.
3. It highlighted the power of nonviolent resistance as a tool for challenging colonial oppression.

End of the Movement:
1. The non-cooperation movement came to an abrupt end in 1922 following the Chauri Chaura incident, where a group of protestors turned violent and attacked a police station, resulting in the death of several policemen.
2. Mahatma Gandhi called off the movement, as he believed that violence went against the principles of nonviolence and peaceful resistance.