Between 1815 and 1819, there was a series of disturbances around Britain. Political meetings were held to protest to the government and to demand reforms. The climax came in 1819, when 60,000 people gathered at St. Peter's Fields, Manchester. The main speaker at the meeting was Henry Hunt, a leading political reformer. The crowd gathered to hear Hunt speak about reform.

However, the local magistrates decided to arrest Hunt. They used the local yeomanry (part-time cavalry) to seize him. In the chaos that followed, eleven people died and many were injured. This event soon became known as ‘Peterloo’, after Britain's recent victory at the Battle of Waterloo (1815).