Excerpts from Books and Wikipedia
"Two ships carrying seventy heavily armed Norman soldiers and Welsh archers arrived in the calm waters of Bannow Bay, on the southeast coast of Ireland in 1169. The troops on board intended to reinstate Dairmait Mac Murchada to the throne of Leinster from which he had been ousted a few years earlier. Mac Murchada had first fled to Wales and then to France, where he had found that the English king, Henry II, was happy to lend him political and military support. . . . The Angevin king himself therefore arrived in Waterford in 1171 at the head of a large army. The king proclaimed Waterford and Dublin royal cities, and toured the whole island. As he did so, he made the rulers of all the Irish kingdoms swear allegiance to him, while his son John (later King John) became lord of Ireland (king of Ireland after Henry's death). In 1175 a treaty was signed at Windsor to confirm the English presence in Ireland, which has remained until modern times." [1001 Days]