I do not think there was ever a more wicked war than that waged by the United States on Mexico. I thought so at the time, when I was a youngster, only I had not moral courage enough to resign. –Ulysses S. Grant, 1879

Grant was a young officer in his twenties when he fought in the U.S.-Mexican War. John Bidwell, who served in the California Battalion, agreed with him, calling the war “an unjustifiable war.”

In A Wicked War: Polk, Clay, Lincoln, and the 1846 Invasion of Mexico, author Amy S. Greenberg uses extensive research and good storytelling to bring to life the people, the conflict, and especially the political pressures that involved the United States in a war of aggression against a neighboring republic.

James K. Polk was a dark horse candidate for president in 1844, but he had tapped into the Zeitgeist of Manifest Destiny. Americans wanted expansion — they wanted more land, land for farmers, land for slaveholders, the resources those lands held and the ports on the Pacific. Polk believed in Manifest Destiny. For Polk, the issue was “a perfect marriage of politics and conviction.” It would win him the presidency.

Texas, which had declared itself an independent republic, was asking for annexation to the United States. But the previous administration had waffled on the issue, not wanting to aggravate Mexico, which still claimed Texas, and reluctant to open more territory to slavery. Polk had no such qualms. He was willing to claim the lie that Mexico had insulted and robbed the United States in order to further a war. For the first time, the United States began a war for empire.

Greenberg follows the army into Texas and Mexico, but her focus is on the political, rather than the military, battle. She has almost nothing to say about the war in California. She draws deft portraits of the major players: Polk, his intelligent and devoted wife Sarah, Henry Clay, Nicholas Trist, who negotiated the treaty with Mexico, Abraham Lincoln, and his rival for office, John J. Hardin. If Hardin had survived as a war hero, Lincoln might never have won his own dark horse candidacy.

A Wicked War is exciting, well-written history, and for me it illuminated the political background of the conquest of California. I heard about the book by listening to the History of California podcast, and was happy to find that my public library has the book.