After the United States Navy's seizure of the cities of southern California, the Californios formed irregular units, which were victorious in the Siege of Los Angeles, and after the arrival of the United States Army, fought in the Battle of San Pasqual and the Battle of Domínguez Rancho. But the Californios were defeated in subsequent encounters, the battles of Río San Gabriel and La Mesa. The southern Californios formally surrendered with the signing of the Treaty of Cahuenga on January 13, 1847. After twenty-seven years as part of independent Mexico, California was ceded to the United States in 1848 with the signing of the Treaty of Guadalupe Hidalgo. The United States paid Mexico $15 million for the lands ceded.