The 18th century saw the beginnings of two changes that would greatly affect Wales, the Welsh Methodist revival, which led the country to turn increasingly nonconformist in religion, and the Industrial Revolution. During the rise of the British Empire, 19th century Southeast Wales in particular experienced rapid industrialisation and a dramatic rise in population as a result of the explosion of the coal and iron industries. Wales played a full and willing role in World War One. The industries of Empire in Wales declined in the 20th century with the end of the British Empire following the Second World War, while nationalist sentiment and interest in self-determination rose. The Labour Party replaced the Liberal Party as the dominant political force in the 1920s. Wales played a considerable role during World War Two along with the rest of the United Kingdom of Great Britain and Northern Ireland and the Allies, and its cities were bombed extensively during the Nazi Blitz. The nationalist party Plaid Cymru gained momentum from the 1960s. In a 1997 referendum Welsh voters approved the devolution of governmental responsibility to a National Assembly for Wales which first met in 1999. In May 2020, the National Assembly for Wales was officially renamed to Senedd Cymru or the Welsh Parliament (simply Senedd), to reflect significantly increased devolution and administrative power.