A union of former colonies itself, the United States approached imperialism differently from the other Powers. Much of its energy and rapidly expanding population was directed westward across the North American continent against English and French claims, the Spanish Empire and Mexico. The Native Americans were sent to reservations, often unwillingly. With support from Britain, its Monroe Doctrine reserved the Americas as its sphere of interest, prohibiting other states (particularly Spain) from recolonizing the newly independent polities of Latin America. However, France, taking advantage of the American government's distraction during the Civil War, intervened militarily in Mexico and set up a French-protected monarchy. Spain took the step to occupy the Dominican Republic and restore colonial rule. The Union victory in the Civil War in 1865 forced both France and Spain to accede to American demands to evacuate those two countries. America's only African colony, Liberia, was formed privately and achieved independence early; Washington unofficially protected it. By 1900 the US advocated an Open Door Policy and opposed the direct division of China.