It was during O'Dwyer's tenure as Lieutenant Governor of Punjab that the Jallianwala Bagh massacre occurred in
Amritsar on 13 April 1919, three days after the onset of the riots. A detachment of 50
British Indian Army soldiers under the command of Brigadier-General
Reginald Dyer fired on a crowd in Amritsar, killing more than 3,000 people. According to then
civil surgeon Dr Smit 1,526 people had been killed. O'Dwyer was informed of the event at 3 am the following day. When he received Dyer's initial report, O'Dwyer gave permission to General
William Beynon to send a telegram to Dyer that stated "your action correct and the lieutenant-governor approves". O'Dwyer and several other senior colonial officials supported Dyer's actions both initially, when only limited information had been received, and later, when more detailed information of the scale of the killings became available. As a result, his actions are considered one of the most significant factors in the rise of the
Indian independence movement, led by
Mahatma Gandhi. One theory surrounding the massacre, as described by
Pearay Mohan and historian Raja Ram, is one of a "premeditated plan" conspired by O'Dwyer and others, including a young Punjabi youth
Hans Raj. Other historians including Nick Lloyd,
Anita Anand and
Kim A. Wagner have found that theory to lack evidence and that there was no conspiracy that Hans Raj was an "
agent provocateur". O'Dwyer had contended without evidence that Dyer's violent suppression of the civilian demonstration was justified because the illegal gathering was part of a premeditated conspiracy to rebellion, which was timed supposedly to coincide with a rumoured Afghan invasion. Although O'Dwyer had implemented martial law in the Punjab, he denied responsibility for the consequences on the grounds that the government had relieved him of its general implementation. However, he could not disclaim responsibility for the decision, after severe rioting in
Gujranwala, to send an aeroplane to bomb and strafe the area. During the course of the operation, at least a dozen people, including children, were killed. In December 1923 the Limerick Brigade of the
Irish Republican Army informed the IRA's Chief of Staff that O'Dwyer would be killed while he was staying with his brother at the family farm in Barronstown. The letter noted that "shooting is too good for him". The action was not carried out however amidst the turmoil within the organisation due to the
Irish Civil War. ==O'Dwyer v. Nair==