Early Tennessee area explorers came from Spain, England, and France. Spain did pursue its claims to the territory as vigorously as France and England. In the middle of the 18th century, the latter two empires used Indians as allies to fight for control. Under the terms of the Treaty of Paris in 1763, France abandoned its claim to the territory to the British. During the War for Independence, soldiers from Tennessee crossed the Great Smoky Mountains and helped to defend South Carolina against the British in the Battle of Kings Mountain. Following the war, the people of Tennessee were dissatisfied with the assistance they were receiving from North Carolina, under whose jurisdiction they were supposed to be governed. In 1784, they formed the unauthorized State of Franklin. In 1789, North Carolina gave the territory to the United States, which formed a territorial government. Tennessee entered the Union as the 16th state in 1796. Black slaves worked on farms in the western and central parts of Tennessee before the Civil War. Those in the eastern part did not own slaves. As a result, there was a division of sentiment in Tennessee during the Civil War. Tennessee was the last state to secede, which it did two months after the outbreak of hostilities. After the war, Tennessee was the first state to be readmitted to the Union. During The Great Depression, President Roosevelt pushed legislation through Congress to create the Tennessee Valley Authority. The TVA improved the lives of many citizens of Tennessee and neighboring states by building dams to control flooding and generate electricity. One of the greatest users of TVA power during World War II was Oak Ridge, a city built in secret by The Manhattan Project for the development of the first atomic bomb.