The United Irishmen organisation in Carlow led by a young brogue-maker named Mick Heydon who had taken over the leadership following the arrest of the previous leader, Peter Ivers, who was arrested with several other leading United Irishmen at Oliver Bond's house in March of that year, had assembled on the night of the 24th and set off at dawn to attack the county town.

A strong party of military was stationed in the court house which is now known as the Deighton Hall (this is situated immediately to the north of the bridge across the river Burrin).

In Dublin Street and to the north, well-armed loyalists filled some large strong houses, but without military support, as the attack was known to be weak from that quarter.

When the Rebels entered the town of Carlow they were joined not only by the Catholic inhabitants but also by people who had secretly arrived there during the previous day and night.

The survivors tried to escape by breaking through adjoining houses and cabins which were set alight by the pursuing soldiers causing the deaths of 200 of the inhabitants.

One survivor William Farrell wrote of the carnage; I know a man as gentle as any who woke to realize his house was on fire [and] threw on some clothes and ran to the street carrying his young daughter.

But just as they made the movement to go on, there were two sentries at the Collector's house, a little below them in Tullow Street, and one of them presented his piece and fired, and killed one of the party, and this single shot stopped the whole body.

They proceeded to Ballickmoyler instead, some miles outside Carlow but in the county Laois and there they set fire to many loyalist houses and attacked the home of John Whitty, a Protestant clergyman.