Laudabiliter was a bull issued in 1155 by Pope Adrian IV, the only Englishman to have served in that office. Existence of the bull has been disputed by scholars over the centuries; no copy is extant but scholars cite the many references to it as early as the 13th century to support the validity of its existence. The bull purports to grant the right to the Angevin King Henry II of England to invade and govern Ireland and to enforce the Gregorian Reforms on the semi-autonomous Christian Church in Ireland. Richard de Clare ("Strongbow") and the other leaders of the Norman invasion of Ireland (1169–71) claimed that Laudabiliter authorised the invasion. These Cambro-Norman knights were retained by Diarmuid MacMorrough, the deposed King of Leinster, as an ally in his fight with the High King of Ireland, Ruaidrí Ua Conchobair.