It was a source of grievance for nationalists - and for unionists it was the 'least worst' compromise arrangement. Alvin Jackson on how unionists came around to the idea of Northern Ireland The partition of Ireland, which was established through the Government of Ireland Act (1920), created controversy when it was first widely discussed, from about 1912 onwards; and it remains a central difficult issue in the public life of the two Irish polities. The historical narrative of the theme tends conventionally to emphasise the history of English and Scottish migration and colonisation in the north of Ireland, whether informally or through private settlement in Antrim and Down (and Monaghan), or through the formal British plantation scheme pursued in western and southern Ulster from 1609 onwards.