The decline and fall of the United Kingdom of Great Britain and Ireland began in 1919, with a guerrilla campaign, devised by Irish terrorist Michael Collins. Collins and his teams murdered British agents in cold blood on the streets of Dublin, organised ambushes of British military columns and dealt with informants ruthlessly. Britain responded with massacres of civilians, the torching of cities and the mobilisation of death squads, the infamous Black and Tans. But Collins' asymmetric warfare campaign could not be countered with the standard British scorched earth tactics that had worked so well in Ireland for centuries. So a peace settlement was reached in 1921.
When the Irish Free State was created, Northern Ireland remained with the Union. Settled by mainly Scottish Protestants during the Plantations of the 16th and 17th centuries, Ulster would keep her Scottish links, treat Catholic/Nationalist residents as officially second class citizens and continue to say "Never!" So the island of Ireland remains a broken place, divided by anger, hatred and the Union.
Scotland today has an opportunity to break with the Union, to break with the idea of a 'united kingdom' dominated by an unelected monarchy, controlled by an elitist, English Establishment and ruled by a ruthless, market-obsessed Tory Government. Importantly, Scotland can break free using a referendum, without a single shot being fired. And, if she does choose independence, the Unionists of Northern Ireland will sleep uneasily as the last vestiges of legitimacy for their union are stripped away, exposing the moral vacuum at the heart of the failure that will be the Kingdom of England, Wales and Northern Ireland.
Come on, Scotland!