English colonization in Ireland set an unfortunate precedent for English colonization in America. The Anglo-Normans (descendants of the Normans who conquered England itself in 1066) arrived in Ireland in 1169 at the request of an Irish king. The king needed help in one of his ongoing conflicts, but he soon discovered that he had made a huge mistake in reaching out to England.
English King Henry II quickly decided that Ireland would make an excellent addition to his realm, and he moved in and took over, annexing Ireland into the English empire. Henry began handing out Irish land to his supporters, and other Englishmen followed suit, seizing more and more land and forcing the now-colonized Irish firmly into the status of second-class (or third-class or fourth-class) citizens and often into poverty. English leaders were busy elsewhere and ignored the situation. The Irish were inferior anyway, they believed, and didn't merit assistance or respect.
The situation worsened when England became Protestant. The Irish held fast to their Catholicism, tensions increased dramatically, and violence often exploded. When English King Charles I began imposing heavy taxes on Ireland, the Irish were furious, because English citizens were not experiencing the same taxation. The burden fell on Ireland, which was already suffering greatly under English rule. Charles's successor, Puritan Oliver Cromwell, destroyed the remainder of the Irish Catholic landholders through his harsh policies of confiscation.
Much of this should sound familiar, for many of the same principles, attitudes, and actions apply to the English colonization of America. When settlers first arrived on the East Coast, they claimed the land for themselves. Never mind the people already settled there, they thought, for the Native Americans were merely heathens and certainly inferior. The English could take their land without a second thought, just like they did in Ireland, and force the former occupants off. Tensions, of course, rose, and violence broke out. The English had not learned the lesson of Ireland.
Of course, the tables soon turned on the English colonists when their king and Parliament started placing the burden of heavy taxes on their shoulders, just as they had in Ireland. The colonies, after all, were for the benefit of the empire, not the other way around, and leaders believed that they could exploit them without any explanation, just as they had done in Ireland.