On this day, 178 years ago, September 14, 1847 (August 6, 1847 in the lunar calendar), during the US-Mexico War, American troops occupied Mexico City. The Mexican-American War was a war between the United States and Mexico that broke out from 1846 to 1848. Through this not-so-large-scale war, the United States seized 2.3 million square kilometers of land and became a major country across the Atlantic and Pacific Oceans, a rare sight in the world. Mexico has lost most of its territory and its vitality has been greatly damaged. The United States has since gained dominance in the Americas. Texas was originally part of Mexican territory, but later Texas unilaterally declared independence and requested to join the U.S. Federation. The United States rejected Texas's application many times due to domestic slavery problems at the time and avoiding war with Mexico, and later accepted Texas's application after the problem was resolved. On May 23, Mexico declared war on the United States. On May 18, 1846, Taylor led U.S. troops south to occupy Matamos, captured Monterrey in September, and occupied Saltillo in November. In June of the same year, Carney led 1700 U.S. troops westward to capture Mexico and California. In February 1847, Taylor's troops defeated a 14,000-strong Mexican army led by Mexican President Santana in Buenos Vista. In March, U.S. military commander-in-chief Scott led 10,000 U.S. troops to land in Veracruz in the Gulf of Mexico. On the 29th, U.S. troops captured Veracruz. On April 18, the U.S. military defeated the main force and staff of President Santana. On May 5, the U.S. military occupied Puebla and approached Mexico City. In August, U.S. reinforcements arrived, and the U.S. military defeated the Mexican army again at Contreras. The two sides held peace talks, and the talks broke down on September 7. On September 8, the U.S. military launched an attack on Mexico City and was repelled. On the 12th, the U.S. military occupied the highland outside the city and bombarded the city wall. On September 14, 1847, the U.S. military invaded Mexico City, and on the 16th, it took control of the city and imposed military control. In October, the Mexican president was removed from office. On November 11, 1847, Anjo was elected interim president of Mexico, and in January 1848, the two sides began peace talks. On February 2, the two sides signed a peace treaty, and Mexico ceded Texas, New Mexico, and California. On June 12, 1848, the U.S. military withdrew from Mexico City and the war ended. Through this not-so-large-scale war, the United States seized 2.3 million square kilometers of land and became a major country across the Atlantic and Pacific Oceans, a rare sight in the world. Mexico has lost most of its territory and its vitality has been greatly damaged. The United States has since gained dominance in the Americas.