In 1598 Caulfeild accompanied the Earl of Essex to Ireland, in command of a troop of horse, and was for a time stationed at Newry. In 1601, under Lord Mountjoy, he took part in the recapture of Kinsale from the Spanish invaders. Mountjoy left Caulfeild in charge of a bridge built by him over the River Blackwater, in command of 150 men, where the fort erected for its protection was called Charlemont.[1]
He had, in 1608, been appointed to the command of the upper part of Tyrone and of Armagh. On 17 April 1613 he was named a privy councillor, and the same year he was chosen knight of the shire for County Armagh in the Irish Parliament. On 19 February 1615 he was made master of the ordnance and on 10 May of the same year one of the council for the province of Munster. Subsequently, he was appointed a member of the commission for the parcelling out of escheated (confiscated) lands.[1]
In consideration of his services to the crown, Caulfeild was created Baron Charlemont and, as he had not married, the succession of the honour was granted to his nephew, Sir William Caulfeild, son of his brother James. He died on 17 August 1627, and was buried in Christ Church Cathedral, Dublin.[1]