The first decades were marked by Jacobite risings which ended with defeat for the Stuart cause at Battle of Culloden in 1746. In 1763, Great Britain in the Seven Years War led to the growth of the First British Empire. With the defeat by the United States, France and Spain in the War of American Independence, Britain lost its 13 American colonies and rebuilt a Second British Empire based in Asia and Africa.  As a result, culture of the United Kingdom, and its technological, political, constitutional, and linguistic influence, became worldwide.  Politically, the central event was the French Revolution And its Napoleonic aftermath, 1793–1815, which British elites saw as a profound threat, and worked energetically to form multiple coalitions that finally defeated Napoleon in 1815. The Tories, who came to power in 1783, remained in power (with a short interruption) until 1830. Forces of reform, often emanating from the Evangelical religious elements, opened decades of political reform that broadened the ballot, and opened the economy to free trade. The outstanding political leaders of the 19th century included Palmerston, Disraeli, Gladstone, and Salisbury.  Culturally the Victorian era (Queen Victoria reigned 1837–1901) was a time of prosperity and dominant middle-class virtues when Britain dominated the world economy and maintained a generally peaceful century, 1815–1914. The First World War (1914–1918), in alliance with France, Russia and the United States, was a furious but ultimately successful total war with Germany. The resulting League of Nations was a favorite project in Interwar Britain. However, while the Empire remained strong, As did the London financial markets, the British industrial base began to slip behind Germany and especially the United States. Sentiments for peace were so strong that the nation supported appeasement of Hitlers Germany in the late 1930s, until the Nazi invasion of Poland in 1939 opened the World War II. In the World War II 1939–45, France, the Soviet Union the U.S. joined Britain as Allies of World War II. Britain and its Empire faced near defeat at several points, 1940–42, but finally crushed Germany, Italy and Japan.
Question: How many years passed between the end of the First World War and the beginning of World War II?
Answer: 21