Step 1: Recall the event.
The Chauri Chaura incident was a violent clash during India's freedom struggle, in the time of the Non Cooperation Movement led by Mahatma Gandhi.
Step 2: The date.
It took place on 4 February 1922.
Step 3: What happened.
Police fired at a group of protesters. In anger the crowd set fire to a police station, and some policemen died in the fire.
Step 4: The place.
This town, Chauri Chaura, lies in the Gorakhpur district. Today this area is part of Uttar Pradesh.
Step 5: The effect.
Gandhi believed strongly in non violence, so he was very upset. He called off the whole Non Cooperation Movement after this event.
Step 6: Conclusion.
So the incident happened at Gorakhpur in Uttar Pradesh.
Answer: Gorakhpur, Uttar Pradesh