Magellan set sail from Spain in 1519 to find a western sea route to Asia, believing the world was round. He wanted to prove this theory, spread Christianity, and find gold and silver. In 1521, Magellan's fleet became the first to sail through the body of water now known as the Strait of Magellan, connecting the Atlantic and Pacific oceans. However, Magellan died later that year in the Philippines. His voyage proved the world was round and established the first circumnavigation, while also connecting the Pacific and Atlantic via the new route through the Strait of Magellan, revolutionizing global trade and navigation.