On April 13, 1919 hundreds of Indians were massacred by the British colonial troops under general Reginald Dyer, the "Butcher of Amritsar". Considering the need to cause terror to prevent any rebellions in Punjab, General Dyer gave orders to shoot on the crowd gathered to attend a rally in Jallianwala Bagh, a narrow square of the city, without firing warning shots and until exhaustion of the ammunition. The troops then withdrew without providing any medical assistance to the wounded.

During the disciplinary proceedings against the general Dyer by the "Disorders Inquiry Committee", specially constituted by the British Government in India, no measures were taken against him because his actions were tolerated by his superiors even if, as a result of the investigation, the officer was relieved of command on March 23, 1920 and retired on July 17, 1920 retaining the rank of colonel.

On February 20, 2013 the British Prime Minister David Cameron visited the memorial of the Jallianwala Bagh massacre, describing it as "a deeply shameful event in British history," but avoiding to condemn it, to present an official apology and to offer reparations to the relatives of the victims. Furthermore, the visit of the British Prime Minister took place during a trip that had as its main purpose the development of trade relations, including the promotion of the multi-role fighter Eurofighter Typhoon.

On February 21, 2013, the British Prime Minister David Cameron also said that the United Kingdom does not intend to return the Koh-i-Noor diamond, even if India already demanded its return on several occasions.

Colonialism Reparation calls on the UK to apologize and pay reparations to India for the massacre of Jallianwala Bagh and for the whole period of British colonial rule, also returning the cultural property stolen during the colonial period.