The conquest of the American frontier is one of the most exciting and dramatic stories in American history. Settling western lands required nearly a century of warfare and hardship as Americans fought the British and many Indian groups to lay claim to the West. The United States was born out of the Revolutionary War, which was fought in part to guarantee the rights of colonists to settle west of the Appalachian Mountains. Yet winning the war and declaring independence from England didn't automatically open the West to the Americans. For four decades after they declared their independence in 1776, Americans battled the British and a variety of Native American groups to take possession of the lands stretching west to the Mississippi River.

The Louisiana Purchase of 1803 and the American victory in the War of 1812 opened the continent to western expansion. The Louisiana Purchase nearly doubled...