Anglo-Norman invasion of Ireland

The Anglo-Norman invasion of Ireland took place during the late 12th century, when Anglo-Normans gradually conquered and acquired large swathes of land from the Irish, over which the kings of England then claimed sovereignty, all allegedly sanctioned by the papal bull Laudabiliter.^[1] At the time, Gaelic Ireland was made up of several kingdoms, with a High King claiming lordship over most of the other kings. The Anglo-Norman invasion was a watershed in Ireland's history, marking the beginning of more than 800 years of direct English and, later, British, conquest and colonialism in Ireland.

In May 1169, Anglo-Norman mercenaries landed in Ireland at the request of Diarmait mac Murchada (Dermot MacMurragh), the deposed King of Leinster, who sought their help in regaining his kingship. They achieved this within weeks and raided neighbouring kingdoms. This military intervention was sanctioned by King Henry II of England. In return, Diarmait had sworn loyalty to Henry and promised land to the Normans.

In 1170, there were further Norman landings, led by the Earl of Pembroke, Richard "Strongbow" de Clare. They seized the important Norse-Irish towns of Dublin and Waterford, and Strongbow married Diarmait's daughter Aoífe. Diarmait died in May 1171 and Strongbow claimed Leinster, which Diarmait had promised him. Led by High King Ruaidrí Ua Conchobair (Rory O'Conor), a coalition of most of the Irish kingdoms besieged Dublin, while Norman-held Waterford and Wexford were also attacked. However, the Normans managed to hold most of their territory.

In October 1171, King Henry landed with a large army to assert control over both the Anglo-Normans and the Irish. This intervention was supported by the Roman Catholic Church, who saw it as a means of ensuring Irish religious reform, and a source of taxes. At the time, Irish marriage laws conflicted with those of the broader Church, and the Gregorian Reform had not been fully implemented. Henry granted Strongbow Leinster as a fiefdom, declared the Norse-Irish towns to be crown land, and arranged the synod of Cashel to reform the Irish church. Many Irish kings also submitted to him, likely in the hope that he would curb Norman expansion, but Henry granted the unconquered kingdom of Meath to Hugh de Lacy. After Henry's departure in 1172, fighting between the Normans and Irish continued.

The 1175 Treaty of Windsor acknowledged Henry as overlord of the conquered territory and Ruaidrí as overlord of the remainder of Ireland, with Ruaidrí also swearing fealty to Henry. The Treaty soon collapsed: Norman lords continued to invade Irish kingdoms and the Irish continued to attack the Normans. In 1177, Henry adopted a new policy. He declared his son John to be the "Lord of Ireland" (i.e. claiming the whole island) and authorised the Norman lords to conquer more land. The territory they held became the Lordship of Ireland, part of the Angevin Empire. The Normans' success has been attributed to military superiority and castle-building, the lack of a unified opposition from the Irish and the support of the church for Henry's intervention.^[2]