Explanation

in February 1922, Gandhi himself called off the movement.

A mob of people at Chauri – Chaura (near Gorakhpur) clashed with police and burnt 22 policemen on February 5, 1922.

This compelled Gandhiji to withdraw from the Non-Cooperation movement on Feb. 12, 1922. 

Gandhiji had to stop his Non-co-operation movement because the people became violent at Chauri-Chau.

Non-cooperation movement started in 1920.