Amritsar 1919: An Empire of Fear and the Making of a Massacre. By Kim Wagner. Yale University Press; 360 pages; $32.50 and £20.

O N THE AFTERNOON of April 13th 1919 General Reginald Dyer led a column of troops and armoured cars through the streets of ancient Amritsar, holy city of the Sikh faith. Their destination was a dusty, enclosed clearing called the Jallianwala Bagh. Failing to squeeze the vehicles and machine-guns through a narrow entrance, Dyer entered with just the soldiers. Before them was a crowd of about 15,000 peaceful, unarmed Indian men, women and children quietly listening to political speeches. Many had come out of idle curiosity.

Dyer, however, saw something very different: a “defiant and murderous mob,” as Kim Wagner puts it in “Amritsar 1919”, “one which had only days before run rampant through Amritsar and which still had the blood of Englishmen on its hands.” Barely pausing, Dyer gave the order to fire. After ten minutes and 1,650 rifle rounds, at least 379 people lay dead; hundreds were injured. Dyer offered no medical help to the wounded. His duty done, he left abruptly.

The Amritsar massacre was probably the most murderous single act in the history of the British Empire. The facts are not in doubt, but its meaning remains hotly disputed. British bigwigs have visited Amritsar to pay their respects, but despite many promptings there has never been an official apology. Indeed, to apologists for empire, this was merely an aberration. As Winston Churchill commented at the time, the slaughter might have been a “monstrous event”, but it was also without parallel “in the modern history of the British Empire…an event which stands in singular and sinister isolation.” Recent historians have taken the same line.

“Amritsar 1919” aims to show how profoundly misleading Churchill’s interpretation was. Mr Wagner maintains that Dyer acted as a loyal servant of a colonial administration founded on terror and violence, particularly in the years after what the British called the “Indian Mutiny” and Indians the “First War of Independence” of 1857. Then the massacre of European women and children at Cawnpore had horrified the British, and the revolt was stamped out with extreme savagery. Thereafter the Raj was paranoid about another insurrection, and its officers, such as Dyer, often acted disproportionately, largely out of fear. This is what happened at Amritsar.

Provoked by the expulsion of two local leaders, three days earlier a mob had indeed run riot through the city, killing three British men and assaulting a woman. There was no evidence that this presaged a wider revolt, yet, haunted by the mutiny, this is exactly what Dyer and other officers believed. When he came upon the gathering at the Jallianwala Bagh, he sincerely thought he had “stumbled upon nothing less than the epicentre and hotbed of the rebellion”. He wanted to get his retaliation in before the imaginary insurgents turned on his soldiers.

This, Mr Wagner reminds readers, is why Dyer was feted as a hero by most Anglo-Indians, and by many in Britain. He had shot dead hundreds of civilians, but other officers had contemplated bombing Amritsar as well. By heading off another mutiny, he had saved the Raj. A London newspaper raised £26,000 for him, a huge sum. Meanwhile some Indians later rejected the relatively paltry amounts that were offered to the victims as compensation.

Mr Wagner argues his case fluently and rigorously in this excellent book. The centenary would be as good a time as any to apologise for Amritsar. In Mr Wagner’s telling, such contrition might apply to many other acts of cruelty and violence visited upon Britannia’s imperial subjects.