In 1839 the Chartists presented to Parliament a petition signed by 1,280,000 people. Merthyr Tydfil alone contributed 14,710 signatures. When Parliament rejected the petition, riots took place all over Britain. In Llanidloes, local Chartists were so angry they took control of the town for a week.

Henry Vincent, one of the Chartist leaders in Wales, was arrested and imprisoned in Monmouth gaol. In November 1839, Chartists in the coalfields of South Wales decided to hold a large demonstration in Newport where they planned to demand the release of Vincent and other Chartists who had been arrested.

The authorities in Newport heard rumours that the Chartists were armed and planned to seize the town. Stories also began to circulate that if the Chartists were successful in Newport, it would encourage others all over Britain to follow their example.

When the marchers arrived in Newport on November 4, they discovered that the authorities had made more arrests and were holding Chartist leaders in the Westgate Hotel. The Chartists marched to the hotel and began chanting "surrender our prisoners". Soldiers had been placed inside the Westgate Hotel and when the order was given, they began firing into the crowd, killing over 20 people.

John Frost, Zephaniah Williams and William Jones, the leaders of the Chartist demonstration, were arrested, tried and sentenced to be hanged, drawn and quartered. Later they were reprieved and transported to Tasmania for life.