The United Kingdom of Great Britain and Ireland was established on 1 January 1801 under the terms of the Acts of Union 1800, by which the nominally separate kingdoms of Great Britain and Ireland were united. In 1922, twenty-six of thirty-two counties of Ireland seceded to form the Irish Free State (later becoming the Republic of Ireland) and, to reflect the change in the United Kingdom’s boundaries, the Royal and Parliamentary Titles Act 1927 formally amended the name of the UK Parliament to the “Parliament of the United Kingdom of Great Britain and Northern Ireland”. The period began with the newly formed United Kingdom defeating France in the Napoleonic Wars. As a direct result of this, the British Empire became the foremost world power for the next century. Great Britain and the north-east of Ireland industrialised rapidly, whereas the rest of Ireland did not, deepening economic and social disparities between them. A devastating famine, exacerbated by government inaction in the mid-19th century led to demographic collapse in much of Ireland, and increased calls for Irish land reform and the devolution of executive power. During and after the Great War, the rise of Irish nationalism and republicanism eventually culminated in the Irish War of Independence, and in 1922, the partition of Ireland between the newly founded Irish Free State and the north-east, which opted to remain part of the United Kingdom as Northern Ireland.