On 16 August 1819 armed cavalrymen and soldiers attacked a very large peaceful crowd in St Peter's Fields in Manchester. Local radicals had called a meeting as part of a campaign for the political reform of parliament, a campaign given renewed vigour by the distressed economic conditions since the end of the Napoleonic Wars. This campaign was particularly strong in the new northern towns such as Manchester where handloom weavers found themselves impoverished as wages fell.
The meeting had scarcely begun before the town authorities - fearful of an uprising - ordered the arrest of the main speaker, Henry Hunt, and sent in the Manchester Yeomanry and regular army to clear the crowd. In the crush and chaos at least 18 people were killed, whilst many hundreds were wounded.
This unprecedented massacre was dubbed 'Peterloo' by the radical press, contrasting this shameful episode with the Allied victory at Waterloo four years earlier.
When the poet Shelley heard about Peterloo he wrote an angry poem, The Masque of Anarchy , although it was not published until 1832. In later years it became a popular recitation at radical and socialist meetings.