Which war resulted in the United States acquiring half of Mexico's territory?

The war that resulted in the United States acquiring half of Mexico's territory is the Mexican War. This conflict, which occurred from 1846 to 1848, was primarily driven by the U.S. desire to expand its territory westward, a concept known as Manifest Destiny. The war concluded with the Treaty of Guadalupe Hidalgo, where Mexico ceded a substantial portion of its northern territory to the United States, including present-day California, Arizona, New Mexico, and parts of Colorado, Utah, and Nevada. This significant territorial gain played a pivotal role in shaping the boundaries of the modern United States.

In contrast, the Civil War was primarily a conflict over issues such as slavery and states' rights, and did not involve territorial expansion from another nation. The Revolutionary War was fought for American independence from British rule, and while it resulted in the acquisition of certain lands, it did not involve the territory of Mexico. Lastly, the War of 1812 was a conflict against Britain for various grievances, including trade restrictions, but again did not lead to the acquisition of Mexican land.