The battle is fought between a Royalist army under the James Butler, 12th Earl of Ormonde, and Richard Butler, 3rd Viscount Mountgarret, who leads Confederate Irish troops raised during the Irish Rebellion of 1641. Ormonde and Mountgarret are cousins, both being members of the Butler dynasty.
Ormonde’s troops leave Dublin on April 2 and march unopposed from Naas to Athy and on to Maryborough, now Portlaoise, arriving on April 8. There they resupply the royalist garrisons and send cavalry forces to support those at Carlow and Birr, before returning to Athy on April 13. Setting out at 6:00 AM on April 15, and having decided to avoid a battle on their return march to Dublin, the government troops are blocked by Mountgarret’s rebel militias at Kilrush, two miles south of Suncroft, between Kilcullen and Moone in southeastern County Kildare.
The land is remarkably flat, with the exception of two ridges that run nearly parallel northward from a castle, with a marsh lying between. The army of Ormonde, consisting of 2,500 foot soldiers and 500 horses, assembles on the high grounds of Ardscull, Fontstown, and Kilrush, while the rebel army under Mountgarret, consisting of 8,000 foot soldiers and 400 horses, proceeds in the same direction along the heights of Birtown, Ballyndrum, Glasshealy, and Narraghmore. Mountgarret, having the advantage in numbers, and anxious for battle, outmarches Ormonde’s forces, and posts himself on Bull Hill and Kilrush, completely intercepting Ormonde’s further progress to Dublin. A general engagement becomes unavoidable. The left wing of the Irish is broken by the first charge. The right wing, animated by their leaders, maintains the contest for some time, but eventually falls back to neighbouring Battlemount. Here they break, flee and are pursued with great slaughter across the grounds they had marched over the previous day. Ormonde’s army then marches on to Dublin, arriving on April 17.
Ormonde’s army suffers twenty fatalities and approximately forty wounded in the Battle of Kilrush. Mountgarret’s rebel army loses more than 700, among which are several colonels. The victory is considered of such consequence that Ormonde is presented with a jewel valued at £50 by the Irish Government.
(Pictured: Sir Peter Lely’s oil painting of James Butler, 12th Earl of Ormonde)