Political map of North America & the Caribbean 18 August 1846 (Conquest of California & New Mexico): At the outbreak of the Mexican-American War, the US had sent a cavalry force to cross the continent (Army of the West (1846)) and a naval squadron into the Pacific (Pacific Squadron), intending both forces to meet in the Mexican territory of Alta California. However the local Mexican governors offered minimal resistance and both California (Conquest of California) and the neighboring territory of New Mexico (Capture of Santa Fe) fell well before the US forces could unite.