In the 1100s, Ruaidrí Ua Conchobair was the high king. He forced Diarmaid Mac Murchada, the king of Leinster, to leave his kingdom. Diarmaid asked Henry II, a Norman king of England, to help him get his land back. Henry agreed, so an army of Norman (and Welsh) knights invaded Ireland in 1167. Richard de Clare, called Strongbow, led the knights. Henry thought the Norman knights and Strongbow were too powerful, so he decided to take over Ireland. He traveled to Ireland with his own fleet in 1171. Henry conquered Ireland and gave it to his youngest son John. Henry thought John would never be king of England, so he made John Lord of Ireland. But John became king of England in 1199 after all his brothers died. After that, Ireland was ruled by the English king. Norman lords from England started taking over more of Ireland. They mostly lived near the east and south coasts, and some land was still ruled by Irish kings.