The end of the Napoleonic Wars in 1815 had resulted in periods of famine and chronic unemployment, exacerbated by the introduction of the first of the Corn Laws. By the beginning of 1819, the pressure generated by poor economic conditions, coupled with the relative lack of suffrage in Northern England, had enhanced the appeal of political radicalism. In response, the Manchester Patriotic Union, a group agitating for parliamentary reform, organised a demonstration to be addressed by the well-known radical orator Henry Hunt.
Shortly after the meeting began local magistrates called on the military authorities to arrest Hunt and several others on the hustings with him, and to disperse the crowd. Cavalry charged into the crowd with sabres drawn, and in the ensuing confusion, 15 people were killed and 400–700 were injured. The massacre was given the name Peterloo in an ironic comparison to the Battle of Waterloo, which had taken place four years earlier.
Historian Robert Poole has called the Peterloo Massacre one of the defining moments of its age. In its own time, the London and national papers shared the horror felt in the Manchester region, but Peterloo's immediate effect was to cause the government to crack down on reform, with the passing of what became known as the Six Acts. It also led directly to the foundation of The Manchester Guardian (now The Guardian), but had little other effect on the pace of reform. In a survey conducted by The Guardian in 2006, Peterloo came second to the Putney Debates as the event from radical British history that most deserved a proper monument or a memorial. Peterloo is commemorated by a plaque close to the site, a replacement for an earlier one that was criticised as being inadequate as it did not reflect the scale of the massacre.
In 1819, Lancashire was represented by two members of parliament (MPs). Voting was restricted to the adult male owners of freehold land with an annual rental value of 40 shillings or more – the equivalent of about £80 in 2008 – and votes could only be cast at the county town of Lancaster, by a public spoken declaration at the hustings. Constituency boundaries were out of date, and the so-called rotten boroughs had a hugely disproportionate influence on the membership of the Parliament of the United Kingdom compared to the size of their populations: Old Sarum in Wiltshire, with one voter, elected two MPs, as did Dunwich in Suffolk, which by the early 19th century had almost completely disappeared into the sea. The major urban centres of Manchester, Salford, Bolton, Blackburn, Rochdale, Ashton-under-Lyne, Oldham and Stockport, with a combined population of almost one million, were represented by either the two county MPs for Lancashire, or the two for Cheshire in the case of Stockport. By comparison, more than half of all MPs were returned by a total of just 154 owners of rotten or closed boroughs. In 1816, Thomas Oldfield's The Representative History of Great Britain and Ireland; being a History of the House of Commons, and of the Counties, Cities, and Boroughs of the United Kingdom from the earliest Period claimed that of the 515 MPs for England and Wales 351 were returned by the patronage of 177 individuals and a further 16 by the direct patronage of the government: all 45 Scottish MPs owed their seats to patronage. These inequalities in political representation led to calls for reform.
After the end of the Napoleonic Wars in 1815, a brief boom in textile manufacture was followed by periods of chronic economic depression, particularly among textile weavers and spinners (the textile trade was concentrated in Lancashire). Weavers who could have expected to earn 15 shillings for a six-day week in 1803, saw their wages cut to 5 shillings or even 4s 6d by 1818. The industrialists, who were cutting wages without offering relief, blamed market forces generated by the aftershocks of the Napoleonic Wars. Exacerbating matters were the Corn Laws, the first of which was passed in 1815, imposing a tariff on foreign grain in an effort to protect English grain producers. The cost of food rose as people were forced to buy the more expensive and lower quality British grain, and periods of famine and chronic unemployment ensued, increasing the desire for political reform both in Lancashire and in the country at large.