in the siege of Yorktown. His surrender on October 19, 1781, led to peace negotiations in Paris and secured the independence of the colonies. Virginians were instrumental in the new country's early years and in writing the United States Constitution. James Madison drafted the Virginia Plan in 1787 and the Bill of Rights in 1789. Virginia ratified the Constitution on June 25, 1788. The three-fifths compromise ensured that Virginia, with its large number of slaves, initially had the largest bloc in the House of Representatives. Together with the Virginia dynasty of presidents, this gave the Commonwealth national importance. In 1790, both Virginia and Maryland ceded territory to form the new District of Columbia, though the Virginian area was retroceded in 1846. Virginia is called the "Mother of States" because of its role in being carved into states such as Kentucky, which became the fifteenth state in 1792, and for the numbers of American pioneers born in Virginia. Civil War Between 1790 and 1860, the number of slaves in Virginia rose from around 290 thousand to over 490 thousand, roughly one-third of the state population during that time, and the number of slaveholders rose to over fifty thousand, both the most in the U.S. Soil exhausted by years of monoculture tobacco farming pushed the plantation economy to expand westward, and as labor-intensive cotton came to dominate southern agriculture after 1800, Virginia plantations turned to exporting slaves by the thousands, breaking up many families in the process and making the breeding of slaves, often through rape, a profitable business for their owners, especially as new federal laws restricted the importation of slaves. In addition to agriculture, slave labor was increasingly used in mining, shipbuilding, and other industrial jobs. The failed slave uprisings of Gabriel Prosser in 1800, George Boxley in 1815, and Nat Turner in 1831, however, marked the growing resistance to the system of slavery. Afraid of further uprisings, Virginia's government in the 1830s encouraged free Blacks to migrate to Liberia. On October 16, 1859, abolitionist John Brown led a raid on an armory in Harpers Ferry, Virginia, in an attempt to start a slave revolt across the southern states. The polarized national response to his raid, capture, trial, and execution in Charles Town that December marked a tipping point for many who believed the end of slavery would need to be achieved by force. Abraham Lincoln's 1860 election further convinced