Towards the end of April, 1691, a detachment of the regiment, commanded by Lieut.-Colonel Hamilton, accompanied a party under Colonel Brewer in a sudden advance towards Dunore, to surprise two thousand armed Roman Catholic peasantry, who had taken post near that place. At daybreak on the following morning the detachment approached the post, and the enemy formed for battle, but soon fled, and the soldiers pursued and killed about fifty fugitives. Quitting Mullingar in the early part of June, the regiment was engaged in the operations of the army under Lieut.-General Baron De Ghinkel, afterwards Earl of Athlone:[13] it took part in the siege of _Ballymore_, which place was captured in a few days; and afterwards appeared before _Athlone_, in the siege of which fortress it had several men killed and wounded. A strong detachment of the regiment took part in the capture of _Athlone_ by storm, on which occasion the assailants rushed through the rapid stream of the Shannon, which was breast high, carried the enemy's works in gallant style, and in less than half an hour were masters of the town, to the surprise of General St. Ruth, who commanded King James's army, which was encamped near the fortress, and who was giving a public entertainment in his camp, when the news of the loss of _Athlone_ reached him. After putting the captured fortress in repair, the army marched towards the enemy, who occupied a strong position near the castle of _Aghrim_, and on the 12th of July a general engagement took place, in which the Irish forces were overpowered and driven from the field with severe loss, including General St. Ruth, who was killed by a cannon ball. On this occasion the regiment formed part of the brigade under Major-General Talmash: it had seven rank and file killed; one major, two captains, one lieutenant, one ensign, and eight rank and file wounded. After this victory, the army marched to _Galway_, which surrendered in a few days; and the victorious English troops proceeded to _Limerick_, where the remains of the defeated Irish forces had assembled, and appeared determined to make a resolute stand, in the hope of being reinforced from France. The regiment had the honour to take part in the siege of Limerick; and, the army having crossed the river Shannon and completed the investment of the place, the Irish soon afterwards surrendered the city, and with it every other part of Ireland of which they retained possession, the Irish regiments being permitted to follow King James to France, or remain in their own country, as they should choose: the "Royal Regiment of Ireland" was one of the corps which proceeded to France, and was taken into the service of Louis XIV. The EARL OF MEATH'S, now EIGHTEENTH regiment, was the only one of the eleven Irish corps embodied by King Charles II. which remained in the service of the English crown.