Conquest of California
The Conquest of California, also known as the Conquest of Alta California or the California Campaign, was a military campaign during the Mexican–American War carried out by the United States in Alta California (modern-day California), then part of Mexico, lasting from 1846 to 1847, and ending with signing of the Treaty of Cahuenga by military leaders from both the Californios and Americans. == Background == When war was declared on May 13, 1846, between the United States and Mexico, it took almost three months for definitive word of Congress' declaration of war to reach the Pacific coast.