In 1688, at the eve of the Glorious Revolution, he was sent with his battalion to England in an effort to provide James with reliable Catholic troops. After James's flight Hamilton made his way back to Ireland where he was promoted to major-general and given the command of the dragoons, under Justin McCarthy, Viscount Mountcashel, in actions around Enniskillen. At some stage his unit was garrisoned in Belturbet, County Cavan. In the battle of Newtownbutler on 31 July 1689, serving under McCarthy, he was wounded in the leg at the beginning of the action, and his dragoons were routed. He succeeded in making good his escape. Hamilton was considered to have led his dragoons into an ambush by over-confidence; and to have made minimal efforts to extricate them. With Captain Lavallin from Cork he served as scapegoat for the defeat, being subjected to a court martial under General de Rosen. Given his family's influence Hamilton was acquitted, while the hapless Lavallin was shot. However, the reputations of the Hamilton brothers had suffered terminal damage with the French.