John C. Calhoun was an American politician and political theorist born on March 18, 1782, in South Carolina. He served as the seventh Vice President of the United States under both John Quincy Adams and Andrew Jackson. Calhoun was a strong advocate for states' rights and played a significant role in the development of the nullification theory, which argued that states could invalidate federal laws they deemed unconstitutional. Throughout his career, Calhoun held various important positions, including Secretary of War and Senator. He was a prominent defender of slavery and believed it was essential to the Southern economy. His ideas and policies significantly influenced the political landscape of the antebellum United States.