New Spain Spain, at 42d north (now the northern boundary of the U.S. states of California, Nevada, and Utah). In the 1821 Declaration of Independence of the Mexican Empire, both Mexico and Central America declared their independence after three centuries of Spanish rule and formed the First Mexican Empire, although Central America quickly rejected the union. After priest Miguel Hidalgo y Costilla's 1810 Grito de Dolores (call for independence), the insurgent army began an eleven-year war. At first, the Criollo class fought against the rebels. But in 1820, a military coup in Spain forced Ferdinand VII to accept the authority of the
Mexican–American War could not be released from its obligations. The US was released from all obligations of Article XI five years later by Article II of the Gadsden Purchase of 1853. The 1848 Treaty of Guadalupe Hidalgo ended the war and enforced the Mexican Cession of the northern territories of Alta California and Santa Fe de Nuevo México to the United States. Mexico acknowledged the loss of what became the State of Texas and accepted the Rio Grande as its northern border with the U.S. The losses amounted to one-third of its original territory from its 1821 independence. Before the secession of