Ivan Gibbons’s book “Partition: How and Why Ireland Was Divided” provides insights into the factors that led to the division of Ireland into two countries. The book, offering interesting lessons on institutional reform, public opinion shifts, and the contingency of history, elucidates on the surprising low cross-border mobility between Northern Ireland and the Republic of Ireland, attempts of Home Rule, rapidly shifting public opinion towards violent republicanism, short-lived expectations of the partition, and the provisionality of the border.
  

Key Points: 

1. Cross-border mobility is surprisingly low between Northern Ireland and the Republic of Ireland. Despite no regulatory and linguistic barriers, only 2.1% of Northern Ireland’s population was born in the South, and only 1.3% of the Republic’s population was born in the North. This suggests the existence of a border has a psychological impact on mobility.
2. Home Rule, a limited form of independence where Ireland would remain in the UK but control areas like taxation and education, was a concept that almost happened. It was voted on four times in the House of Commons, passing in 1914 but delayed indefinitely due to WWI. The last Home Rule bill of 1920 established partition in law.
3. Public opinion shifted rapidly towards violent republicanism. Despite initial unpopularity and favoring of Home Rule, factors such as constant delays, enlistment of nationalists in WWI, and British handling of the 1916 Rising led to increasing popularity of full independence and political violence.
4. Many believed the partition would not last long. At the time, it was viewed as an imperfect solution with a potential for change. However, around 1932, the window to change the form of partition mostly closed.
5. The border with Northern Ireland was intended to be provisional. Some villages, and even plots of land, were suddenly split into two countries. The British and Irish governments established the Boundary Commission to study and recommend a redrawing of the border, which was a term of the 1921 Anglo-Irish Treaty that granted Ireland its independence.

Source: https://www.thefitzwilliam.com/p/five-lessons-from-the-partition-of