In the first part of the 18th century, French explorers and fur traders began to enter the plains west of the Missouri River. In 1714, Étienne de Veniard, Sieur de Bourgmont became the first European to reach the Platte River. Spain, which had claimed "ownership" of the Great Plains since the Coronado expedition of the 16th century, worried about the expansion of French influence in the region. In 1718, the War of the Quadruple Alliance broke out between France and Spain.