On 13 April 1919, the day of the Sikh festival of Vaisakhi, British soldiers fired indiscriminately on unarmed men, women and children attending a peaceful public meeting in a walled park called Jallianwala Bagh, in Amritsar, Punjab. An estimated 1,000 people were killed and many more injured as they were shot in cold blood, even as they tried to escape.

In the years that have followed, those British politicians who have spoken of the massacre at all have portrayed it as a “monstrous” exception to the otherwise benign rule of the British Raj – arrogantly dismissing Britain’s long and bloody record of colonial repression in India. British descriptions of colonial history are rife with such convenient denials and reframings. Even that pivotal conflict India’s first war of independence, which started in 1857 and lasted two and a half years, was dubbed “the mutiny” and is still described as such in British history books.

Its significance, however, was enormous. Not only did it shape new forms of colonial racism, giving rise to tropes of natives as evil terrorists, but because Hindus and Muslims had jointly fought the British, it created a long-lasting fear of Hindu-Muslim unity. The war shaped the key methods of control for the rest of British control – divide and rule on the one hand, brutal violence sanctioned by draconian laws on the other.

The events of 1919 were directly shaped by these policies. It was a time of intense repression all over India, but particularly in Punjab. The Rowlatt Act had just been passed, allowing for arrest and imprisonment without trial or evidence. Two popular anticolonial leaders were arrested and interned outside Punjab. In this atmosphere, as historian Dr Kim Wagner writes in his recent book about the massacre, a few days before the arrests, at the Hindu festival of Ram Navami, Hindus and Muslims had drunk water, milk and sherbet from the same vessels as a marker of unity. Thousands raised slogans of “Hindu-Musalman ki jai!” (“victory to Hindus and Muslims!”).

Far from any expression of regret, the massacre was followed by the imposition of brutal collective punishment – “crawling orders” – which forced people to crawl face downwards along a street where a missionary had been attacked some days earlier.

Visitors peer inside the Jallianwala Bagh martyrs’ well ahead of the 100th anniversary of the Jallianwala Bagh massacre Photograph: Narinder Nanu/AFP/Getty Images

With time, the British succeeded in creating polarisation along religious lines. In 1915 and 1925, respectively, two Hindu-supremacist organisations were formed – the Hindu Mahasabha and the Rashtriya Swayamsevak Sangh (RSS). The latter was modelled on Mussolini’s blackshirts, and is the still-active parent organisation of today’s ruling Bharatiya Janata party (BJP). It had the blessings of the colonialists and remained pro-British throughout the struggle for freedom. It was VD Savarkar, the RSS ideologue, who first demanded the partition of India.

Today, 72 years after independence, the legacies of colonial rule are still starkly present in India. A large number of colonial-era laws are still in use, some have been retained unchanged, others altered in name only. Even the notorious Rowlatt Act lives on as the Unlawful Activities (Prevention) Act. It was used recently against Dr GN Saibaba, a disabled academic and human rights campaigner now serving a life sentence under appalling conditions. The sedition laws used against anticolonial leaders are frequently used against today’s dissenters, from indigenous environmental activists to students. The draconian Armed Forces Special Powers Ordinance used by the British to imprison Gandhi is today the Armed Forces Special Forces Act, which allows the Indian army to kill and maim with impunity in Kashmir.

Meanwhile, protesters are not only criminalised but can be gunned down, as when plain-clothes police officers fired on local people protesting against a polluting copper-smelting factory owned by a subsidiary of the multinational mining company Vedanta.

As for the Hindu-supremacist RSS, its plethora of affiliated storm troopers have transformed BJP-ruled India into a republic of fear, where lynchings and rapes of Muslims, Dalits and Christians are common occurrences. As the country begins its general election, the belligerence of these killer gangs and the virulent Islamophobia of many politicians of the ruling party is only escalating.

Against this background, as we remember those who were killed in the Jallianwala Bagh massacre, let us remember their commitment to unity across India’s diverse faiths, and their courage to stand up for it against all odds.

• Amrit Wilson is a writer and activist