We are what we remember. The massacre of men, women and a child at St Peter’s Field in Manchester, 200 years ago on Friday, had a seismic impact and has reverberated ever since. Around 60,000 people – half the local population on some counts – had gathered for a peaceful, orderly and legal rally; 18 died and hundreds were wounded as sabre-wielding cavalry charged into the crowd. Women had played a striking role in organising the meeting, and casualties were disproportionately female.

Its memory was mobilised in the campaigns for successive reform acts, and invoked by suffragettes; Labour’s evocation of a future made by “the many not the few” echoes Shelley’s The Masque of Anarchy, written in anguished response to the slaughter. The meeting grew out of the broader ferment across the north, driven by dire economic straits, yet was an explicitly political demand for representation. Now, those who memorialise it know that universal suffrage is necessary but not sufficient, and politics needs new ways of addressing economic injustice.

Why, then, does this massacre still matter in 2019? The broad answer is that modern Britain does not know or think enough about its history. In the conservative island story, Peterloo is often ignored. It is rarely taught in schools. It challenges the narrative that Britons won democracy by piecemeal, peaceful reform. That version treats protest and crowds as a distraction from the forward march of enlightened British greatness.

Play Video 9:25 A massacre that changed Britain: does Peterloo still resonate today? – video

But Britain has other traditions. Peterloo is a particularly bloody example of many other confrontations – some bigger, many smaller, some for noble causes, others for ignoble ones, some more violent, many more peaceful – which are just as much a part of the complex tapestry of history as kings, queens, battles and great inventions. This narrative stretches from the peasants’ revolt through Peterloo to the marches against Brexit, with many stops along the way and down many historical byways.

The immediate aftermath saw increased repression. The key speaker, Henry Hunt, was jailed; the Six Acts sought to prevent large meetings and gagged newspapers; it was their powerful accounts of events (one by John Edward Taylor, who would launch the Manchester Guardian two years later), which had led to public outrage. But the massacre and ensuing crackdown discredited the political system more utterly than an unhindered meeting could ever have done. The governing classes themselves recognised the cost: the state still carried out violent suppressions, but would shy from the use of lethal force on the British mainland. It opened the eyes of many in the middle class to the need for reform. It showed workers just how essential basic political rights were. It helped to catalyse the political change that began with the 1832 Reform Act that gave cities like Manchester representation at Westminster, and which culminated in universal suffrage in 1928.

Ten years ago, when the artist Jeremy Deller organised a procession in Manchester, one group of marchers held high the banner: “Our ancestors were at Peterloo.” It was in part a literal, local statement. But it also recognised, as we should today, that those who fell in Manchester helped us rise.