On July 7, 1846, a contingent of Marines raised the American flag over Monterey, California, to mark a proclamation by U.S. consul Thomas Larkin that the territory was being annexed as a consequence of the war with Mexico. Much of the future state had already been taken from Mexico's nominal control by an uprising of American settlers under the Bear Flag. Victory in the Mexican War meant that the country gained Texas, California, and everything in between, comprising most of what is now New Mexico, Arizona, Nevada, Utah, Colorado, and Wyoming. Next to the War of Independence and the Civil...