Indians had helped the English during the First World War. They believed that after the War the British would grant them independence. But they were highly disappointed by the Montague declaration.
The Government passed the Rowlatt Act according to which any person could be imprisoned without trial. On April 13, 1919 there was strike all over the country. People of Amritsar held a protest meeting in Jallianwala Bagh. General Dyer gave shooting orders without a prior warning to people. Hundreds of people were killed in this massacre that evoked a nationwide resentment.