George Washington a notorious hero of the American Revolutionary War, commander in chief of the Continental Army, and president of the Constitutional Convention became the first President of the United States under the new U.S. establishment. The Whiskey Rebellion in 1794, when settlers in the Monongahela River valley of western Pennsylvania protested against a central tax on liquor and distilled drinks, was the first serious test of the federal government. The Louisiana Purchase, in 1803, gave Western farmers use of the significant Mississippi River waterway, removed the French presence from the western border of the United States, and provided U.S. settlers with vast potential for expansion. In response to continuous British impressments of American sailors into the British Navy, Madison had the Twelfth United States Congress led by Southern and Western Jeffersonian declare war on Britain in 1812. The United States and Britain came to a draw in the War of 1812 after bitter fighting that lasted until January 8, 1815. The Treaty of Ghent, officially ending the war, basically resulted in the maintenance of the status quo ante bellum; however, crucially for the U.S, the British ended their alliance with the Native Americans.
The Monroe Doctrine, expressed in 1823, proclaimed the United States opinion that European powers should no longer settle or interfere in the Americas. This was a defining moment in the foreign policy of the United States. The Monroe Doctrine was adopted in response to American and British fears over Russian and French extension into areas of the Western Hemisphere. It was not until the Presidential Administration of Teddy Roosevelt that the Monroe Doctrine became a central tenet of American foreign policy. The Monroe Doctrine was then invoked in the Spanish-American War as well as later in the proxy wars between the United States and Soviet Union in Central America. In 1830, Congress passed the Indian Removal Act, which certified the president to negotiate treaties that exchanged Indian tribal lands in the eastern states for lands west of the Mississippi River.
This established Andrew Jackson, a military hero and President, as a cunning tyrant in regards to native populations. The act resulted most notably in the forced migration of several native tribes to the West, with several thousand Indians dying en route, and the Creeks’ violent opposition and eventual defeat. The Indian Removal Act also directly caused the ceding of Spanish Florida and next led to the many Seminole Wars. Mexico refused to accept the annexation of Texas in 1845, and war broke out in 1846. The U.S., using regulars and large numbers of volunteers, defeated Mexico which was badly led, short on resources, and plagued by a divided command. Public emotion in the U.S. was divided as Whigs and anti-slavery forces opposed the war. The 1848 Treaty of Guadalupe Hidalgo ceded California, New Mexico, and adjacent areas to the United States. In 1850, the issue of slavery in the new territories was settled by the Compromise of 1850 brokered by Whig Henry Clay and Democrat Stephen Douglas.