The Seminole Wars were a series of three military conflicts between the United States and the Seminoles that took place in Florida between about 1816 and 1858. The Seminoles are a Native American nation which coalesced in northern Florida during the early 1700s, when the territory was still a Spanish colonial possession. Tensions grew between the Seminoles and American settlers in the newly independent United States in the early 1800s, mainly because enslaved people regularly fled from Georgia into Spanish Florida, prompting slaveowners to conduct slave raids across the border. What began as small cross-border skirmishes became the First Seminole War, as Andrew Jackson led U.S. forces into Florida—despite Spanish objections—to pursue the Seminoles. Jackson's forces destroyed several Seminole, Mikasuki and Black Seminole towns, as well as captured San Marcos de Apalache and briefly occupied Pensacola before withdrawing in 1818. In 1819 the U.S. and Spain agreed to transfer Florida in the Adams–Onís Treaty.