The Battle of Prosperous, a military engagement between British Crown forces and United Irishmen rebels, takes place in the town of Prosperous, County Kildare, on May 24, 1798, during the Irish Rebellion of 1798.

Prosperous is founded by Sir Robert Brooke in 1780 as a village for processing cotton produced in the Americas. When a rebellion spearheaded by the United Irishmen breaks out against British rule in Ireland, rebel forces led by John Esmonde make plans to capture Prosperous. Esmonde has 200 rebels under his command, while Prosperous is garrisoned by elements of the Royal Cork City Militia under the command of Captain Richard Swayne and reinforced by detachments of a Welsh mounted fencible regiment, the Ancient British Regiment of Fencible Cavalry Dragoons (also known as the Ancient Britons), numbering 150 men in all.

On May 24, 1798, Esmonde leads his forces to attack Prosperous. Their entry is preceded by the infiltration of a small rebel vanguard, who with the possible help of female sympathisers residing in Prosperous, scale the walls of the town’s barracks, kill the sentries and open the town gates. The barracks are quickly surrounded and attacked by the rebels who repulse an attempt by the garrison to break out. “Swayne himself was surprised in bed, shot and piked to death and his body burned in a tar barrel.” The remainder of the garrison are trapped in the upper floors of the barracks which is set on fire by the rebels, causing them to jump in desperation onto the ground below, where they are summarily executed with pikes. While the rebels suffer no known casualties, approximately 40 members of the garrison are killed in the battle.

Ten members of the garrison, all belonging to the Ancient Britons, manage to escape from Prosperous to Dunlavin, County Wicklow, where they participate in the Dunlavin Green executions on May 26. Esmonde is later captured by Crown forces and brought to Dublin for trial. As he had previously enlisted at the rank of lieutenant in the Clane Yeomanry, Esmonde is court-martialled on June 13 and found guilty of being a deserter. He is executed by hanging on June 14 on Carlisle Bridge (now the O’Connell Bridge) with his coat being worn reversed to indicate that he had been convicted of desertion. Prosperous remains under the control of the United Irishmen until June 19, when a detachment of the 5th Dragoon Guards under the command of Lieutenant Colonel Stewart recaptures the town.