Answer:
Udham Singh assassinated Michael O'Dwyer (lieutenant governor of punjab under the british rule) because he was responisible for the 'Jallianwala Bagh Massacre' also known as the 'Amritsar Massacre'. On April 13, 1919, over twenty thousand unarmed Indians, mainly Punjabis , peacefully assembled in Jallianwala Bagh, Amritsar, to listen to several prominent local leaders speak out against British colonial rule in India and against the arrest and deportation of Dr. Satya Pal, Dr. Saifuddin Kitchlew, and few others under the unpopular Rowlatt Act. Udham Singh and his mates from the orphanage were serving water to the crowd on a warm summer afternoon. Army soldiers under the command of Brigadier-General Reginald Dyer opened fire on the people without any prior warning. After witnessing this event, udham took a vow to wreak a vengeance on the perpetrators of the crime. It emerged as a fact that the massacre was premeditated by officials including o'dwyer. And on 13th March 1940, almost 21 years after the Jallianwala Bagh killings, a joint meeting of the East India Association and the Royal Central Asian Society was scheduled at Caxton Hall. Michael O'Dwyer was one of the speakers at the meeting. Udham managed to sneak in a revolver at this meeting and shot Michael O'Dwyer twice, who died immediately.
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