William fitz Roger

William fitz Roger (died after 1295) was an Anglo-Norman cleric, judge and Crown official in late thirteenth-century Lordship of Ireland. He was Prior of the Irish House of the Knights Hospitallers at Kilmainham, and served as a Privy Councillor and as a justice in eyre (itinerant judge). He led several military expeditions (the Hospitallers were an order of fighting monks), but was a notoriously incompetent commander, whose campaigns invariably ended in failure. He served as Deputy Justiciar in 1284–85, and as acting Justiciar of Ireland in 1294.

Early career He is thought to have been a Norman from the Kingdom of England, but little is known of him until 1274, when he was appointed Prior of Kilmainham. There had been a long gap in filling the office: the previous Prior, Henry Kyriell, had died in 1260.

Glenmalure and afterwards

As the head of a great military order, fitz Roger was expected to lead troops in battle, and soon after his appointment he led an expedition against the O'Byrne clan of County Wicklow, who periodically raided Dublin. These raids were always a cause of great concern to the Dublin Government, and the Prior of Kilmainham was one of those entrusted with the city's defences. The expedition was a disastrous failure: most of fitz Roger's forces, including numerous monks, were slaughtered in the valley of Glenmalure in the Wicklow Mountains, and the survivors, including the Prior himself, were taken captive. The Prior acted as Deputy Justiciar from 1284 to 1285, and despite his disastrous failure at Glenmalure, he led further military expeditions in County Offaly and County Roscommon. He was also appointed Custos rotulorum (Keeper of the Rolls). In 1295 he is on record as bringing a number of lawsuits to recover property at Corballis and Athcarne, allegedly belonging to the Order. Little is heard of him after 1295, though his successor as Prior, William Ros or de Rosse, was not appointed until 1301.