During George's reign the break-up of the British Empire and its transition into the Commonwealth of Nations accelerated. The parliament of the Irish Free State removed direct mention of the monarch from the country's constitution on the day of his accession. From 1939, the Empire and Commonwealth, except Ireland, was at war with Nazi Germany. War with Italy and Japan followed in 1940 and 1941, respectively. Though Britain and its allies were ultimately victorious in 1945, the United States and the Soviet Union rose as pre-eminent world powers and the British Empire declined. After the independence of India and Pakistan in 1947, George remained as king of both countries, but the title Emperor of India was abandoned in June 1948. Ireland formally declared itself a republic and left the Commonwealth in 1949, and India became a republic within the Commonwealth the following year. George adopted the new title of Head of the Commonwealth. He was beset by health problems in the later years of his reign. His elder daughter, Elizabeth, succeeded him.