On August 10, 1519, Ferdinand Magellan led five ships and roughly 270 men out of Seville, sailing down the Guadalquivir River toward the Atlantic in search of a westward route to the Spice Islands. Magellan himself would die in the Philippines in 1521, but one battered ship, the Victoria, completed the circumnavigation in 1522, forever proving the Earth's oceans were interconnected.
Magellan's fleet—the Trinidad, San Antonio, Concepción, Victoria, and Santiago—was underfunded, undermanned with quarrelsome Spanish officers resentful of a Portuguese commander, and headed into waters no European had charted. They left Seville on August 10, 1519, though they wouldn't actually clear the mouth of the river and enter the Atlantic proper until early September, anchoring first at Sanlúcar de Barrameda.
What followed was one of the most harrowing voyages in maritime history: a mutiny put down at Patagonia, the discovery of the strait that now bears Magellan's name, months adrift on the Pacific during which starving sailors gnawed leather and ate rats, and Magellan's own death in April 1521, killed by warriors in Mactan, in the Philippines, after wading into a local conflict he didn't need to join.
Of the original five ships and roughly 270 men, only the Victoria returned to Spain in September 1522, commanded by Juan Sebastián Elcano, carrying just 18 survivors and a hold full of cloves. It was the first expedition to circle the globe, proof beyond argument that the Earth's oceans connected into one navigable whole—a fact that would reshape trade, empire, and cartography for centuries.
Key people: Ferdinand Magellan, Juan Sebastián Elcano