Act of Union 1800

Background. Ireland had been in personal union with England since the Crown of Ireland Act 1542, and with Scotland after the Union of the Crowns in 1603. Ireland gained effective legislative independence through the Constitution of 1782, but frustration among the Catholic majority, the 1798 rebellion, and fears that a newly enfranchised Catholic majority would change the character of Irish government pushed British elites toward merging the parliaments. Historian James Stafford traces the union's intellectual foundations to Enlightenment critiques connecting Ireland's exclusion from imperial trade with the penal laws barring Catholics from property and representation.

Legislative Process. A first motion for union was legally rejected in 1799, defeated in the Irish House of Commons by 109 votes to 104. The second vote in 1800 passed by 158 to 115, with contemporary accounts attributing passage in part to peerages and honours awarded to critics. Complementary acts were then enacted: the Union with Ireland Act 1800 by the Parliament of Great Britain and the Act of Union (Ireland) 1800 by the Parliament of Ireland.

Effect and Aftermath. The acts came into force between 31 December 1800 and 1 January 1801, and the merged Parliament of the United Kingdom first met on 22 January 1801. The House of Lords gained four rotating Church of Ireland bishops and 28 elected Irish representative peers, while the House of Commons added 100 Irish members. The Union Flag created by the union remains the United Kingdom's flag.