It shook Cardiff to its core and made headlines across the country.
But you won’t find any statue or plaque in the Welsh capital that recognises the shocking events of June 1919.
That summer, four days of rioting brought murder and mayhem to the streets of the city.
They were sparked by racial tensions during a period of acute unemployment. In Cardiff’s docklands, servicemen who had returned from war found themselves competing for jobs with a local workforce of largely black and Asian men, who were also desperate to make ends meet.
On 11th June 1919 those tensions boiled over. A confrontation between a group of black men and a white crowd triggered mass rioting in the docklands.
At first the violence centred on the multi-ethnic neighbourhood of Tiger Bay. But it quickly spilled over to other parts of Cardiff.
Leslie's mother and grandparents were living in a quiet terraced street in the Grangetown area of the city.
Leslie's grandmother was white; her grandfather was from Barbados.
“A thousand people came rioting down the street looking for black people,” Leslie explains.
“So my grandmother persuaded my grandfather to go out the back way and to climb over the wall and go and hide. She reckoned that nobody would hurt her.
“But they did. They beat her up. They beat her really badly.
“My mother was only nine at the time and she was terrified. She hid behind my grandmother’s skirts.”
The family home was looted. Rioters doused the downstairs rooms with paraffin, planning to set the building on fire. All that stopped them lighting the fuse was the discovery that the house was rented, owned by a white man.
Leslie’s grandmother never recovered from the incident.
“She changed from then onwards. From being a bright, confident woman she became very withdrawn and quiet. She suffered a lot.”
The race riots of 1919 brought bloodshed to Cardiff. Three men died and hundreds more were injured.
That same summer, the South Wales docklands of Newport and Barry also experienced brutal outbreaks of racial violence.
But in modern day Cardiff you won’t find any reminders of those riots. No memorial, no marker. They’ve become a forgotten chapter in the city’s history.
You can see more on this story in Dock of the Bay, Tuesday 6th November at 7:30pm on ITV Cymru Wales. It will then be online at: itv.com/walesprogrammes