The industrialisation of Germany, the Empire of Japan, and the United States contributed to the relative decline of British industrial supremacy in the late 19th century. The start of World War I in 1914 marked the end of the Pax Britannica. However, the British Empire remained the biggest colonial empire until the start of decolonization after World War II ended in 1945, and Britain remained one of the leading powers until the Suez Canal crisis in 1956, during which British and French troops were forced to withdraw from Egypt under pressure from the United States and (to a lesser extent) the Soviet Union.