Thomas Jefferson (April 13, 1743 – July 4, 1826) was the third President of the United States (1801–1809) and the principal author of the Declaration of Independence (1776). Jefferson was one of the most influential Founding Fathers, known for his promotion of the ideals of republicanism in the United States. Jefferson envisioned America as the force behind a great "Empire of Liberty" that would promote republicanism and counter the imperialism of the British Empire.
Major events during his presidency include the Louisiana Purchase (1803) and the Lewis and Clark Expedition (1804–1806), as well as escalating tensions with both Britain and France that led to war with Britain in 1812, after he left office.
