His military reputation was high enough that when he was sent to the Siege of Derry, his arrival was "eagerly communicated" to the defenders "for the purpose of intimidation". He was wounded at Derry, though not seriously, and was present at the Battle of the Boyne the following year. After the Jacobite victory at the Siege of Limerick he was appointed by Tyrconnell as Governor of the city. Success at Limerick led some Jacobites to believe the war could still be won and along with Patrick Sarsfield, Dorrington was one of the main figures in the "War Party", which opposed Tyrconnell's efforts to reach a peace settlement with William. The 1691 campaign opened with a brief but  bloody siege at Athlone; while the Williamite army took the town, the main Jacobite force fell back along the Galway road. The two armies met at Aughrim, County Galway on 12 July; Dorrington and John Hamilton commanded the two divisions of the Jacobite infantry. The Battle of Aughrim ended with the Jacobite forces shattered, Hamilton fatally wounded, and Dorrington captured. While the Williamite commander, Ginkel, had given word to Dorrington that the captives would be treated as prisoners of war, he and other general officers were instead taken to the Tower of London as prisoners of state. The Earl of Ailesbury recorded that Dorrington, a "good friend", "was totally forgotten in France, and became most unhappy". In late 1693 he submitted a petition complaining about his treatment, having been denied rights usually given to prisoners of war; Lucas, the governor of the Tower, was later reprimanded for his "ill-usage" of Dorrington. In February 1694 he successfully escaped from the Tower in disguise aided by a group of Jacobite sympathising "gentlewomen". The "London Gazette" advertised a reward of £300 for his capture, describing him as a "a tall spare Man, aged near 50 or thereabouts, thin Visaged, having a Welt near the lower part of his Right Cheek by a Shot". On his return to France he resumed command of the Foot Guards, now serving in French exile under the terms of the Treaty of Limerick. With the French rank of "Marechal du camp", Dorrington subsequently served in Flanders during the War of the Grand Alliance. Following the Peace of Ryswick which ended the war, the Foot Guards were amalgamated into the Irish Brigade of the French Army as Dorrington's Regiment.