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The Aftermath of War

A Hypothetical Question: Was the U.S.-Mexican War Necessary?

By David M. Pletcher
Indiana University

Photo of U.S. soldiersWhile the U.S.-Mexican War was being fought and for some time afterward, Americans argued heatedly over its morality. President Polk defended his actions stoutly in his war message. An illegal and undemocratic government of Mexico, he said, had refused to negotiate pressing disagreements with the U.S. about debts, claims and boundaries. Mexico had then invaded Texas, a part of the United States, and had killed Americans on American soil. The President concluded: "As war exists, and notwithstanding all our efforts to avoid it, exists by the act of Mexico herself, we are called upon by every consideration of duty and patriotism to vindicate with decision the honor, the rights and the interests of our country."

During and after the fighting, many Americans accepted this interpretation of the war; few would do so now. If asked about the morality of the war, probably most would profess ignorance or otherwise avoid answering. If presented with the evidence, they would reluctantly admit that their side had had a weak case for fighting. Put more baldly, however, this was a war of aggression. Some American expansionists, including President Polk, wanted Mexican territory, mainly California, and thought they could take it by force, although they had no idea of how much force would be required. They satisfied their scruples with a suitable rationalization.

But was it necessary to fight at all for the desired territory? Since its independence, the U.S. had developed a flexible, effective procedure for gradually acquiring territory with a minimum of risk. This procedure was to reinforce its much-vaunted "irresistible progress" with diplomatic and economic pressure or perhaps veiled threats and to exploit fully the disunity among European powers and their lukewarm interest in North America. In each case, the pressure of American westward migration had been an actual or potential force supporting government actions. By 1845, American migration into California had prepared that province for incorporation into the American Union, and the Bear Flag rebellion, awkward and ill-managed though it was, showed how close the province was to revolution and independence.

Why not use this time-proven gradualist procedure in California and the Southwest? There were obstacles. One was the linguistic, religious, and other cultural differences between rough American migrants and the settled, conservative Californian ranchers. Another was the likelihood of Indian fighting against the fierce Southwestern tribes. To judge from Polk's diary and letters, the obstacles that impressed him most were the stubbornness of the Mexican government and Britain's desire to add California to Oregon and control the Pacific coast of North America. A threat of war or, if necessary, a short border conflict might bring the corrupt, deceitful officials in Mexico City to see reason, and speedy action would forestall British plots.

Photograph of maps on a tablePolk might have been able to think more clearly about these obstacles if he had had a more cosmopolitan background. He had been raised in Tennessee, far from the Atlantic coast and its orientation toward Europe. In the lower Mississippi valley, he also inherited a disdain for Spanish and Spanish Americans, whom he regarded as haughty, aristocratic liars. (Slavery and slave territory played little role in his thinking about foreign affairs.) Polk's idea of proper negotiating technique was to take a strong stand, backed up by a threat of force, and maneuver his opponent into submission without offering any compromise. But this was exactly the wrong way to treat the sensitive Mexicans with their feeling of "death before dishonor." Later, after the capture of Mexico City, it was diplomatic persuasion, aided greatly by British influence, that brought the war to an end. As for the British, they had their sense of honor too, and it forbade them to yield territory to which they had a legal claim. Since they had a partial claim to Oregon but none at all to California, it eventually seemed reasonable to them to divide the former and let the Mexicans defend the latter. Polk might have considered also that London had not resisted the American annexation of Texas, where their interests were greater than in California. Most Britons were more interested in American trade than in North American territory anyway.

Polk fought a war against Mexico with an untried army far from home over an unfamiliar terrain. He risked blundering into a stalemate like that which France had faced in trying to set up Maximilian as emperor of Mexico during the 1860s. A less risky alternative was to wait until American migrants into California could occupy that province, create an independent state like Texas, and eventually join the American Union of their own accord. Alone, Mexico could not have prevented this, and European entanglements would have kept England or France from intervening. The liberal revolutions of 1848, the year the war ended, would have been enough to divert European attention for several years.

To be sure, a gradual solution to the American territorial problem, if less risky, was likely also to take longer to complete than a victorious war. Polk was no gradualist, but an impatient man who had promised to serve only one term in office. In the long run, would the American people have been more patient than he as the California Question stretched on and on? Like so many problems in history, we cannot solve this one in retrospect. We know only that a gradual solution would have been less costly in lives than a conflict. It would probably have delayed and might even have avoided the Civil War.