Clark's Shawnee Campaign — Great Miami River (1786)

The early republic period saw the United States move from the weak Articles of Confederation to the federal Constitution ratified in 1788, with the Bill of Rights added in 1791. George Washington served two terms as president (1789–1797), establishing precedents for executive authority, and the federal capital moved permanently to Washington D.C. in 1800. The Louisiana Purchase (1803) doubled the nation's territory for roughly $15 million, opening vast trans-Mississippi lands to American expansion. The War of 1812 against Britain ended inconclusively but produced a surge of American national identity and eliminated most British support for Indigenous resistance east of the Mississippi. The Northwest Indian Wars (1785–1795) and the Creek War (1813–1814) broke Indigenous confederacies that had resisted US expansion. The Missouri Compromise of 1820 temporarily balanced slave and free states as the nation expanded westward, but embedded the contradiction of slavery in every subsequent territorial debate.