Before revision: January 1, 1801 The Kingdom of Great Britain or Great Britain changed its name to United Kingdom of Great Britain and Ireland or United Kingdom on January 1, 1801 due to the Acts of Union 1800.
After revision: ,January 1, 1801 The Kingdom of Great Britain or Great Britain changed its name to United Kingdom of Great Britain and Ireland or United Kingdom on January 1, 1801 due to the Acts of Union 1800.