At first, European colonizing countries followed policies of mercantilism, in order to strengthen the home economy, so agreements usually restricted the colonies to trading only with the metropole (mother country). By the mid-19th century, however, the British Empire gave up mercantilism and trade restrictions and adopted the principle of free trade, with few restrictions or tariffs. Christian missionaries were active in practically all of the colonies because the Colonialists were Christians. Historian Philip Hoffman calculated that by 1800, before the Industrial Revolution, Europeans already controlled at least 35% of the globe, and by 1914, they had gained control of 84%.[3] In the aftermath of World War II, the archetypal European colonial system practically ended between 1945–1975, when nearly all Europe's colonies gained political independence.