The Tonypandy Riot of 1910 was a dispute between miners and mine owners that took place at the Cambrian Colliery mine in South Wales, UK.
The conflict arose when the Naval Colliery Company opened a new seam at the Ely Pit in Penygraig. After a short test period to determine what would be the future rate of extraction, owners claimed that the miners deliberately worked more slowly than they could. The miners on the other hand argued that the new seam was more difficult to work in than others. The miners were paid by the ton of coal removed, not by hours of work.
In August of 1910, owners posted a lock-out notice at the mine. The miners went on strike. The owners then called in replacement workers. The miners responded by picketing the work site. Rioting occurred, and the Chief Constable requested military support from then Home Secretary Winston Churchill. Churchill did send troops, which was exceptional in mainland Britain, and an action for which he was widely criticised at the time and for years afterwards. He did not actually deploy them: instead he deployed large numbers of metropolitan police officers. Stories about troops firing on miners are untrue, but do reflect the deep anger at troops being present at all.
Troops were later deployed during the tension over the trial of thirteen miners for rioting and for 'intimidating a colliery official'. None of the accused got more than a few weeks in prison and the matter died down.