King of Leinster, against Domnall mac Gilla Pátraic, King of Osraige, in Laois. Following this campaign, FitzHenry was then part of his uncle Robert FitzStephen's expedition to aid Domnall Mór Ua Briain, King of Thomond.

In 1171, FitzHenry was part of the group of Anglo-Normans that broke the Siege of Dublin by the attacking army led by Ruaidrí Ua Conchobair,