Thank you for providing details Einstein but you haven't told us why he went to Ireland or why he did what he did. If you look at the situation at the time, the Civil War in England had just come to an end, people were at stalemate rather then living in peace, Scotland(I think, would someone fill in the details?) and Ireland were still fighting the Civil War on behalf of the King. The army had not been paid and was threatening to mutiny plus their continental enemies were just waiting for the opportunity to stick their oar in, Ireland would probably be the best base of operations. Cromwell needed to bring peace to the British Isles and quickly. The siege of Drogheda was meant to be an example to the Irish people and it was hoped that they would surrender if they thought similar actions would be perpetrated around the countryside. There was also an ulterior motive in coming to Ireland, in 1641 a number of Protestant settlers had been massacred, the rumours that reached England placed the numbers in the hundreds of thousands so it was an opportunity to avenge the dead settlers. If anything overshadowed Anglo-Irish politics it was the Plantations that occurred during Cromwells reign, not the sieges because if you look further along the line there were equally bloody battles fought. To take a single event and place that as the shadow over the relationship between our two islands denies the complexity of our relationship.