(a) The Jallianwala Bagh massacre—facts—on 13 April,1919, General Dyer blocked the exit points from the enclosed ground of Jallianwala Bagh where a large crowd had gathered—some to protest against the British government's repressive measures, others to attend the annual Baisakhi fair. Dyer's objective was to "produce a moral effect" and terrorise satyagrahis. Hundreds of innocent people including women and children were killed on this day in the indiscriminate firing by British soldiers. This led to large scale strikes, clashes with police and attacks on government buildings by the enraged Indian people.
(b) The Simon Commission—facts—it arrived in India in 1928 and faced protest slogans of "Go Back Simon". It was because this body was to suggest constitutional changes in Indian governance, but it did not have any Indian members. The Congress and the Muslim League jointly demonstrated against it. Lord Irwin announced a vague "dominion status" for India to quell the movement, leading to a Round Table Conference in October, 1929.