Kentucky was first reached by French explorers, perhaps La Salle as early as 1669. The first Englishman was probably Gabriel Arthur in 1673. Neither the French nor the English were particularly active in the area for the next seven decades, until a race for control developed that led to the French and Indian War. In 1763, France passed the territory to Britain, which quickly prohibited settlement west of the mountains. Nevertheless, Americans began to visit the area and in 1775 the first settlement at Boonesboro was built. For several years, settlers from North Carolina and Virginia vied for control of the area, with jurisdiction finally going to Virginia. After the end of the American Revolution, settlement increased, along with pressure for more local control. In 1789, Virginia agreed to relinquish its claim and Kentucky was admitted to the Union as the 15th state in 1792. It was never a territory, being part of Virginia until the time it became a state. Francois Andre Michaux was a French botanist, son of Andre Michaux, another French botanist. Francois Michaux traveled through Kentucky in 1802 and wrote his observations in a book entitled, Travels to the West of the Alleghanies, published in France in 1804 and later translated into English. He described the Kentucky practice of breeding and raising horses, for which the state has remained famous. The Breckinridge family of Lexington was a major factor in Kentucky politics in the 19th century. John Breckinridge served as attorney general under Thomas Jefferson. His grandson, John C. Breckinridge, became the youngest vice-president ever elected in 1856 and was nominated by the Southern Democrats in 1860, carrying eleven slaves states but not Kentucky itself. Kentucky was not initially a supporter of either the Union or Confederate side in the Civil War. Although the legislature had restricted the importation of slaves as early as 1830, in 1860 nearly 20 percent of Kentucky`s population consisted of slaves. Those parts of the state dominated by relations with Virginia or where large-scale tobacco plantations flourished favored the South, but the majority of Kentuckians chose to remain loyal to the Union. Despite Confederate incursions, by the end of 1862, the Union had undisputed control of all of Kentucky. Coal mining became a major industry in southeastern Kentucky following World War I. In 1936, the federal government established its gold bullion repository at Fort Knox. The University of Kentucky decided in 1949 to allow black and white students to attend classes together.