people of each territory would decide whether or not slavery would be permitted. The compromise also included a more stringent Fugitive Slave Law and banned the slave trade in Washington, D.C. The issue of slavery in the territories would be re-opened by the Kansas–Nebraska Act (1854), but the Compromise of 1850 played a major role in postponing the American Civil War. Background The Republic of Texas declared its independence from Mexico following the Texas Revolution of 1836, and, partly because Texas had been settled by a large number of Americans, there was a strong sentiment in both Texas and the United States for the annexation of Texas by the United States. In December 1845, President James K. Polk signed a resolution annexing Texas, and Texas became the 28th state in the union. Polk sought further expansion through the acquisition of the Mexican province of Alta California, which represented new lands to settle as well as a potential gateway to trade in Asia. His administration attempted to purchase California from Mexico, but the annexation of Texas stoked tensions between Mexico and the United States. Relations between the two countries were further complicated by Texas's claim to all land north of the Rio Grande; Mexico argued that the more northern Nueces River was the proper Texan border. In March 1846, a skirmish broke out on the northern side of the Rio Grande, ending in the death or capture of dozens of American soldiers. Shortly thereafter, the United States declared war on Mexico, beginning the Mexican–American War. In August 1846, Polk asked Congress for an appropriation that he hoped to use as a down payment for the purchase of California in a treaty with Mexico, igniting a debate over the status of future territories. A freshman Democratic Representative, David Wilmot of Pennsylvania, offered an amendment known as the Wilmot Proviso that would ban slavery in any newly acquired lands. The Wilmot Proviso was defeated in the Senate, but it injected the slavery debate into national politics. In September 1847, an American army under General Winfield Scott captured the Mexican capital in the Battle for Mexico City. Several months later, Mexican and American negotiators agreed to the Treaty of Guadalupe Hidalgo, under which Mexico agreed to recognize the Rio Grande as Texas's southern border and to cede Alta California and New Mexico. The Missouri Compromise had settled the issue of the geographic reach of