(Jan. 1, 1801) Legislative agreement uniting Great Britain and Ireland under the name of the United Kingdom of Great Britain and Ireland.
After the unsuccessful Irish revolt of 1798, the British prime minister, William Pitt the Younger, decided that the best solution to the Irish problem was a union to strengthen the connection between the two countries. The Irish parliament resisted the proposal, which called for its abolition, but votes bought by cash or honours ensured passage of the agreement in 1800. The union remained until the recognition of the Irish Free State (excluding six of the counties of the northern province of Ulster) by the Anglo-Irish treaty concluded on Dec. 6, 1921; the union officially ended on Jan. 15, 1922.