On April 13, 1919, British and Imperial troops under the command of General Reginald Rex Dyer gunned down between 400 and 600 Indian protestors at Jallianwala Bagh, a garden near the Golden Temple in the city of Amritsar in the Punjab state of India. Many more protestors were wounded. The shooting lasted for ten minutes. Many were shot as they ran for cover. Some were killed as they tried to scale high walls.

The Amritsar Massacre, Winston Churchill told the House of Commons, was a slaughter, a “monstrous event”, “an episode...without precedent or parallel in the modern history of the British Empire”. British historian AJP Taylor wrote that the massacre was “the decisive moment when Indians were alienated from British rule”.

In her new book The Patient Assassin, longtime BBC journalist Anita Anand uses the Amritsar Massacre as the backdrop to tell the fascinating story of Udham Singh, a low-caste Punjabi orphan who spent the next 21 years planning to avenge those who were killed at Amritsar by assassinating British officials he believed were responsible for the massacre.

On March 13, 1940, at a meeting of the East India Association in the Tudor Room of Caxton Hall in London, Udham Singh murdered Sir Michael O’Dwyer, who was the Lieutenant Governor of Punjab at the time of the massacre and who endorsed and defended the British action. Three other British officials were wounded in the attack.

“The moment [Udham Singh] pulled the trigger,” Anand writes, he became the most hated man in Britain, a hero to his countrymen in India and a pawn in international politics.

Anand views Udham Singh as neither saint nor villain.

Radicalised by the massacre and other manifestations of British repression and resistance to Indian national aspirations, he was also used by militant Indian nationalists, the Comintern and later the Nazis in efforts to weaken and undermine British imperial rule.

The author has personal roots in this story. Her grandfather, a teenager at the time, was in Amritsar on the day of the massacre. He left Jallianwala Bagh shortly before British forces arrived and he lost friends in the attack. Her husband’s family was from Punjab and one of them briefly lived with Udham Singh. Her perspective is very much an Indian one – that doesn’t make it wrong, just incomplete. The British perspective is not entirely missing from her book, but it is given relatively short shrift.

India was the jewel in the British Crown, a symbol of the Empire, yet it was ruled by an exceedingly small British military and political elite who administered the subcontinent through local elites. Britain ruled its empire ruthlessly when necessary and Britain’s political and military officials in India understood their tenuous hold on power.

Anand describes the British attitude as “act early, act decisively, show strength, or risk being swept away” at the first sign of rebellion.

The Indian Mutiny of 1857 provided a lesson in this regard. There, a mutiny by sepoys – Indian soldiers serving in the British army – in Calcutta quickly spread throughout all of northern India. “Rebels rampaged across the region,” Anand notes, “and a minority committed unspeakable atrocities against British civilians”, including the slaughter of more than 200 British women and children at Bibighar. The British government exacted terrible retribution by executing nearly 100,000 sepoys, including many who were innocent of any atrocities.

British officials in April 1919 did not want a repeat of the Sepoy Mutiny. To them, Gandhi’s nonviolent movement for Home Rule was being hijacked by Indian radicals. Two weeks prior to the massacre, anarchy reigned in Delhi. Soon thereafter riots broke out across Punjab. Three days prior to the massacre, after British police arrested Gandhi and two other anti-colonial leaders, mobs in Amritsar terrorized some Europeans and were not stopped by native police. The mob murdered five men, burning three of their corpses in the street and brutally beat and left for dead an elderly female missionary.

On the morning of April 13, General Dyer publicly proclaimed at multiple locations in the city an order banning public meetings and warned that any such assemblies would be dispersed by force. His warnings were ignored as 15,000 people to 20,000 people – many carrying metal-tipped sticks – gathered at Jallianwala Bagh.

To British eyes, Dyer’s actions that day may have prevented a much more widespread rebellion which would have resulted in countless more lives lost. The British action brought calm to the Punjab province within a few days and some Indian shopkeepers and merchants praised Dyer for preventing looting and more destruction. The guardians of the nearby Golden Temple made Dyer an honorary Sikh.

It is not the facts that divide Anand’s and some British viewpoints – it is their differing perspectives.

General Dyer was disciplined and lost his command after a British-led commission found fault with his actions. To Indians, he was the Butcher of Amritsar. To many Britons at the time, he was a sacrificial lamb in an effort to appease the people of India and preserve British rule there. He died a broken man in July 1927.

What is not in doubt is that the Amritsar Massacre further fuelled the fire of Indian nationalism and anti-British sentiment. It did not help matters any that in the years preceding the massacre tens of thousands of Indian troops had bravely served the Empire in the First World War. Was the massacre at Amritsar how the British showed their gratitude?

Resistance to British colonial rule took two main forms: non-violent protests led by Gandhi and his followers who initially sought political autonomy within the British imperial system and the more radical revolutionary movement led by the Ghadar Party which sought the violent overthrow of British imperial rule. Udham Singh gravitated to the Ghadars.

Anand notes that although Udham Singh said he was at the Amritsar Massacre, to this day his true whereabouts on that day are unknown.

Only Udham Singh knows the truth of where he was on the day of the massacre, and during his life he told so many people so many different versions of events that it is impossible to know which, if any of them, is true.

For twenty years after the massacre, Udham Singh, often using aliases, travelled to Africa, to the European continent, to America and to England in an effort “to become the avenging angel for his people”.

He was frequently on the radar screen of various British intelligence services because of his associations with Indian radicals and Russian communists. Anand gained access via Freedom of Information requests to thousands of documents about Udham Singh that British officials wanted sealed forever.

Udham Singh was supported by, and in turn provided services to, the Ghadar Party in India, America and Europe. The Ghadars provided him with money, false identification papers, and friendly places to stay during his journeys. Udham Singh spent five years in a jail in Amritsar after police found him with seditious material and guns. There he met Bhagat Singh, who was awaiting a death sentence for the murder of a British policeman and who had committed an act of terror in the Central Legislative Assembly in Delhi in 1929. Udham Singh called Bhagat Singh his guru and he would be further inspired to carry out his assassination plan by Bhagat Singh’s example.

Udham Singh’s patience finally paid off on March 13, 1940. After he killed Sir Michael O’Dwyer, he confessed to the crime and his motives – the Amritsar Massacre and Indian independence. His trial lasted two days. He was found guilty and condemned to death. He was hanged at Pentonville prison on July 31, 1940. British authorities portrayed him as a lone-wolf terrorist, without political connections or motivations. There was a war to win and hopefully, an empire to be preserved.

Britain won the war but did not preserve the empire. Indian independence was achieved, but not peacefully. Anand notes that liberation from British rule came at a terrible price – 15 million people displaced and two million dead. She mostly blames the British for this. She concludes by noting that in 2017, a statue of Udham Singh was placed at the sight of the massacre. “It depicts him,” she writes, “standing with his arm outstretched, palm up, holding a clod of blood-soaked earth in his hand. A reminder of a promise which took twenty years to fulfil.”

Francis P Sempa is the author of Geopolitics: From the Cold War to the 21st Century and America’s Global Role: Essays and Reviews on National Security, Geopolitics and War. His writings appear in The Diplomat, Joint Force Quarterly, the University Bookman and other publications. He is an attorney and an adjunct professor of political science at Wilkes University.

This article first appeared on the Asian Review of Books.