After repairing the breaches of Ballymore, and putting the place in a state of defence, the army advanced to _Athlone_, and on the 20th of June, the regiment was ordered to support the storming party at the attack of the Westmeath side of the town. Major-General Mackay commanded the troops employed on this service, and after making the necessary arrangements for the attack, took his post on the battery to see the issue, when he observed that the advanced party had missed its way and halted. He instantly hastened to the TWELFTH regiment, and taking the first captain he came to by the hand, pointed the way to the breach. The regiment immediately rushed forward, stormed the breach in gallant style, and overcoming the resistance of the Irish, drove them across the bridge to the Connaught side of the town. Several batteries were raised against the works on the Connaught side of the river, and the grenadier company of the TWELFTH was engaged in forcing the passage of the Shannon, and in capturing the town by storm, on the 30th of June, which was a most desperate service, and was performed with distinguished valour and intrepidity. The Irish army, commanded by a French officer of talent and reputation, General St. Ruth, took up a position near _Aghrim_, where it was attacked on the 12th of July. During the action, Major-General Mackay ordered the TWELFTH, and three other regiments, to pass a difficult bog, ford a rivulet, and drive the Irish from behind the hedges of the nearest enclosures. The soldiers waded through the bog and rivulet, which was waist deep, and drove the Irish out of the first enclosures in gallant style. They afterwards pressed forward with too much ardour, before the troops designed to support them had arrived, and becoming insulated, they were attacked in front and on both flanks by very superior numbers, and driven back to the edge of the bog. The Irish followed, shouting and plying them with musketry; but a support arriving under Major-General Talmash, the four regiments faced about, repulsed their pursuers, and by a spirited effort recovered their lost ground; the cavalry passed the bog near the castle of Aghrim, and by a determined charge completed the overthrow of the Irish army: the French general, St. Ruth, was killed towards the close of the action by a cannon-ball. The TWELFTH regiment had one major, one captain, one ensign, and a number of private soldiers killed, one lieutenant, and seven rank and file wounded. The regiment afterwards marched with the army to _Galway_, and formed part of the force employed in the siege of that place, which surrendered on the 21st, and was delivered up on the 26th of July. Major-General Bellasis was appointed governor of Galway, and the TWELFTH, twenty-second, and twenty-third regiments were selected to form the garrison of that fortress.