Revenue stamps of the United Kingdom
When Ireland was partitioned into Northern Ireland and Southern Ireland in 1921, separate revenue stamps were issued for both entities. Southern Ireland stamps saw little use since that political entity was quickly superseded by the Provisional Government of Ireland and later the Irish Free State (both of which applied overprints on various British and Irish revenue stamps). However, Northern Ireland continued to use separate revenue stamps until the 1980s. Northern Irish revenues include Civil Service, Dog Licence, Excise and National Insurance stamps, among many others.
Decolonization
The independence movement in Ireland and the 19th and early 20th century was marked by occasional outbursts of violence, culminating in the small-scale Easter Rising of 1916 and the much larger Irish War of Independence of 1919 to 1921. It was resolved when London gave independence to the Catholic regions of southern Ireland, and kept control of Protestant Northern Ireland.