The introduction centres on contrasting two pivotal moments in the story of the partition of Ireland, one at the beginning and one at the end of the partitioning process. The first concerns the final copper-fastening of the border with the settlement of the Boundary Commission issue in 1925, while the second revolves around the announcement of the partition plan by Lloyd George six years earlier. In both cases it is shown that the same fundamental questions were raised and unsatisfactory answers provided. This is followed by an examination of why the subject of partition has so often been underplayed in Irish historical writing on the period, arguing that, while the division of the island is fundamental for understanding the nature of modern Ireland, its deep ambiguities made it a subject that did not fit easily into the statist and ideologically driven histories that emerged in its aftermath.