Invading Mexico: America's Continental Dream and the Mexican War, 1846-1848

Popular historian Joseph Wheelan recounts James Polk’s strategy of last resort for prying California away from Mexico. He had tried to buy it; he had instructed his agents to encourage a settlers’ revolt. When these measures failed, the impatient president, while cynically condemning Mexico’s anger over America’s annexation of Texas, sent General Zachary Taylor’s army to the Rio Grande River, into territory that Mexico claimed as hers. By provocatively sending Taylor there, the president got his war — and, as bitter corollaries, the scathing criticism of congressional leaders on moral grounds, and Mexico’s lasting distrust of its powerful northern neighbor.

The Mexican War was America’s first truly modern war. Steamships ferried troops, daguerreotypes captured the spectacle of infantry and cavalry marching off to battle, newspapermen reported from the front lines for the first time, and telegraphs helped speed news of victories to eager readers back home. For the first time, large numbers of the regular Army’s field-grade officers were West Point-trained. Weapons technology advances such as the mobile field artillery, the Colt six-shooter and the Sharp’s Rifle gave the U.S. Army daunting firepower. These advantages ensured victory even when Mexican troops outnumbered Americans by as much as 4-to-1.