Unionism in the United Kingdom, also referred to as British unionism, is a political ideology favouring the continuation of the United Kingdom of Great Britain and Northern Ireland, or in some cases the enlargement of that state to include other countries such as Ireland.
Unionism was historically a major issue in Ireland, where Irish nationalism was a significant force. Most of Ireland gained independence from the UK in the 1920s. In Northern Ireland, which remained part of the UK, unionism has continued to be a major issue and the main political divide is between unionists/loyalists and Irish nationalists/republicans. This has led to violent conflict in Northern Ireland, most notably the Troubles.
Since the late 20th century support for the Union has become a bigger issue in Scotland and, to a lesser extent, Wales. Following the Scottish National Party's victory in Scotland's 2011 election, a referendum on Scottish independence took place on 18 September 2014: the result supported remaining within the United Kingdom, winning the vote by 55.3% No to 44.7% Yes to the question "Should Scotland be an independent country?".
https://en.wikipedia.org/wiki/Unionism_ ... ed_Kingdom