100 years ago today, on 13 April 1919, one of the great defining moments of 20th century British rule in India took place, the Amritsar Massacre.

There were several possible causes, the most compelling being the extension of the First World War state of emergency in India into 1919. Large public gatherings were banned and this coupled with economic distress, the flu epidemic and the return of thousands of Indian troops led to public agitation. Riots broke out in several cities in early April which were put down with violence. 

In Amritsar, the Sikh holy city, rioters destroyed many European-owned businesses and killed five whites with others beaten up and injured. The Lt-Gov of Punjab Province Michael O'Dwyer called in reinforcements under Col. Reginald Dyer. He immediately imposed severe restrictions on public gatherings and movements, but reckoned without a festival planned for 13 April in an area of wasteland, the Jallianwala Bagh.

By 1600 that afternoon a crowd of over 5000 had assembled in the Bagh and were being harangued by speakers calling for the British to leave India. When Dyer heard of this he took 90 men, all either Indian or Gurkha troops, plus two armoured cars equipped with machine guns to the Bagh. However the entrances were too narrow for the vehicles to enter, so he took his men in and ordered all but one of the four entrances to be blocked. 

By 1715 the men were lined up and without warning he opened fire. The shooting lasted no more than ten minutes, the crowd in desperation tried to climb the walls while some even jumped down a well to escape. By the time Dyer gave the order to ceasefire and march out hundreds lay dead or dying, the official casualty figures gave a total of 379 killed and around 1500 wounded, but the actual number of fatalities is probably nearer 500.

Lt-Gov O'Dwyer approved of his actions, but the Indian Government did not, neither London. At the official enquiry Dyer's actions were condemned but no further action was taken against him. In 1920 he was recalled to Britain and retired. By then a public subscription on his behalf organized by the Morning Post had raised £26,000 by those who viewed him as the saviour of British India. He died in 1927.