The Merthyr Rising of 1831 was the violent climax to many years of simmering unrest among the large working class population of Merthyr Tydfil in Wales and the surrounding area.
Throughout May 1831 the coal miners and others who worked for William Crawshay took to the streets of Merthyr Tydfil, calling for reform, protesting against the lowering of their wages and general unemployment. Gradually the protest spread to nearby industrial towns and villages and by the end of May the whole area was in rebellion, and it is believed that for the first time the red flag of revolution was flown as a symbol of workers' revolt.
After storming Merthyr town, the rebels sacked the local debtors' court and the goods that had been collected. Account books containing debtors' details were also destroyed. Among the shouts were cries of Caws a bara (cheese and bread) and I lawr â'r Brenin (down with the king).
On 1 June 1831, the protesters marched to local mines and persuaded the men on shift there to stop working and join their protest. In the meantime, the British government in London had ordered in the army, with contingents of the Argyll and Sutherland Highlanders dispatched to Merthyr Tydfil to restore order. Since the crowd was now too large to be dispersed, the soldiers were ordered to protect essential buildings and people.
On 2 June, while local employers and magistrates were holding a meeting with the High Sheriff of Glamorgan at the Castle Inn, a group led by Lewsyn yr Heliwr (also known as Lewis Lewis) marched there to demand a reduction in the price of bread and an increase in their wages. The demands were rejected, and after being advised to return to their homes, attacked the inn. Engaged by the 93rd (Highland) Regiment, after the rioters seized some of their weapons, the troops were commanded to open fire. After a protracted struggle in which hundreds sustained injury, some fatal, the Highlanders were compelled to withdraw to Penydarren House, and abandon the town to the rioters.