How did the Irish-English conflict come about?

For an indepth answer read Richard English's Irish Freedom. In short it is very complex but the root cause of the British Irish conflict lies in religion, the switch to protestantism on Great Britain, made Catholic Ireland a threat, because the reformation failed there. Both the Old English and Native Irish resisted the change and outside of places like Cork, Ulster and the Pale. It is then a long history of wrongs on both sides which are always followed by some retribution, this in turn makes both sides feel they are a wronged victim and thus righteous in their retribution. Propaganda combined with a poor knowledge of history have often warped facts to give a more divisive view. The answer below being an excellent example of such poor historical knowledge, as it merges the Strongbow expedition with the centuries later plantation of Ireland and also complete misses out the Scots. It is a very complex and interesting history which has no easy answer, and their are frequent points that radical altered the relationship such as the first world war. Ultimately though it was the division in religion that is the origin of the conflict.

The Irish-English conflict began in approximately 1108 AD, an English army landed on the east coast of the country and invaded the country. At this point in history Ireland was a place of great scholarship, it was the "Island of Saints and Scholars". During the English invasion many of the Irish leaders and cheiftans were killed and the English took control of the country. The English sent over thousand of "planters" to colonise the country. To ensure that the Irish people did not revolt against their new masters, the English banned all learning in Ireland. It became illegal for an Irish people to learn how to read or write. Schools were also banned for Irish people and the penalty was death for anyone who tried to teach the basic learning skills.

"The Irish-English conflict began in approximately 1108 AD, an English army landed on the east coast of the country and invaded the country."

Wrong. This never happened. There was an invasion in the 1100's, but it was led by Norman-Welsh men, who's king was French.

"During the English invasion many of the Irish leaders and cheiftans were killed and the English took control of the country. The English sent over thousand of "planters" to colonise the country. To ensure that the Irish people did not revolt against their new masters, the English banned all learning in Ireland. It became illegal for an Irish people to learn how to read or write. Schools were also banned for Irish people and the penalty was death for anyone who tried to teach the basic learning skills."

I am open to correction on this but as far as I understand the King of Leinster (Diarmuid MacMuraidh?) had promised to make a Norman lord (Strongbow) his heir in exchange for military assistance. He went on to become the next King of Leinster. Fearing that Strongbow would set up a rival kingdom to match his own, the King of England, Henry II travelled to Ireland in 1169 to receive homage from Strongbow and assert his control over Ireland. In reality that control only extended to the Dublin and the surrounding areas

When King Henry VIII was not able to have kids with his wife he asked the church for divorce. When church did not gave him permission, he made his own church which was against the Irish people who was catholic didnt wanted to change their religion, hence there was an English Irish conflict.