Udham Singh killed Sir Michael O'Dwyer the former Lieutenant Governor of Punjab on 13 March 1940 at Caxton Hall, Westminster, London.
- O'Dwyer had been Lt. Governor of Punjab at the time of the Jallianwala Bagh Massacre (13 April 1919), in which General Dyer ordered troops to fire on an unarmed crowd, killing hundreds
- O'Dwyer publicly supported Dyer's action Udham Singh killed him to avenge the massacre
- Udham Singh made no attempt to escape; was arrested immediately
- Tried, convicted, and hanged on 31 July 1940 at Pentonville Prison, London
- Called "Shaheed-e-Azam Sardar Udham Singh" a martyr of the Indian independence movement