Soon after Dyer's arrival, on the afternoon of April 13, 1919, some 10,000 or more unarmed men, women, and children gathered in Amritsar's Jallianwala Bagh (bagh, "garden"; but before 1919 it had become a public square) to attend a protest meeting, despite a ban on public assemblies. It was a Sunday, and many neighbouring village peasants also came to Amritsar to celebrate the Hindu Baisakhi Spring Festival. Dyer positioned his men at the sole, narrow passageway of the Bagh, which was otherwise entirely enclosed by the backs of abutted brick buildings. Giving no word of warning, he ordered 50 soldiers to fire into the gathering, and for 10 to 15 minutes 1,650 rounds of ammunition were unloaded into the screaming, terrified crowd, some of whom were trampled by those desperately trying to escape. According to official estimates, nearly 400 civilians were killed, and another 1,200 were left wounded with no medical attention. Dyer, who argued his action was necessary to produce a "moral and widespread effect," admitted that the firing would have continued had more ammunition been available.
The governor of the Punjab province supported the massacre at Amritsar and, on April 15, placed the entire province under martial law. Viceroy Chelmsford, however, characterized the action as "an error of judgment," and when Secretary of State Montagu learned of the slaughter, he appointed a commission of inquiry, headed by Lord Hunter. Although Dyer was subsequently relieved of his command, he returned a hero to many in Britain, especially conservatives, who presented him with a jeweled sword inscribed "Saviour of the Punjab."
The Jallianwala Bagh massacre turned millions of moderate Indians from patient and loyal supporters of the British raj into nationalists who would never again place trust in British "fair play." It thus marks the turning point for a majority of the Congress' supporters from moderate cooperation with the raj and its promised reforms to revolutionary noncooperation. Liberal Anglophile leaders, such as Jinnah, were soon to be displaced by the followers of Gandhi, who would launch, a year after that dreadful massacre, his first nationwide satyagraha ("devotion to truth") campaign as India's revolutionary response.
The positive impact of reform was seriously undermined in 1919 by the Rowlatt Acts, named after the recommendations made the previous year to the Imperial Legislative Council by the Rowlatt Commission, which had been appointed to investigate "seditious conspiracy." The Rowlatt Acts, also known as the Black Acts, vested the viceroy's government with extraordinary powers to quell sedition by silencing the press, detaining political activists without trial, and arresting any suspected individuals without a warrant. No sooner had the acts come into force in March 1919--despite opposition by Indian members on the Imperial Legislative Council--than a nationwide cessation of work (hartal ) was called by Mohandas Karamchand Gandhi (1869-1948). Others took up his call, marking the beginning of widespread--although not nationwide--popular discontent. The agitation unleashed by the acts culminated on April 13, 1919, in Amritsar, Punjab. The British military commander, Brigadier Reginald E.H. Dyer, ordered his soldiers to fire at point-blank range into an unarmed and unsuspecting crowd of some 10,000 men, women, and children. They had assembled at Jallianwala Bagh, a walled garden, to celebrate a Hindu festival without prior knowledge of the imposition of martial law. A total of 1,650 rounds were fired, killing 379 persons and wounding 1,137 in the episode, which dispelled wartime hopes and goodwill in a frenzy of postwar reaction.