On the morning of April 18, about eighty-five hundred United States troops led by Gen. Winfield Scott routed twelve thousand Mexicans at Cerro Gordo. Since capturing the seaport of Veracruz three weeks earlier, the American Army had marched inland virtually unmolested. Meanwhile, Mexico’s charismatic president, Antonio Lopez de Santa Anna, was rallying his scattered forces for a final stand at a mountain pass along the road to Mexico City. They had enough time to set up artillery, and as the Americans approached, their defenses looked formidable. But adept scouting by Lt. Robert E. Lee (who at one point lay motionless behind a log for hours to avoid capture) revealed that a path could be cut through dense wilderness behind the Mexican lines. The Americans attacked from front and rear simultaneously, and within three hours the overwhelmed and shattered Mexicans were fleeing in complete disarray. By April 24, having taken the cities of Jalapa and Perote without resistance, Scott could report that “Mexico no longer has an army.”

Unfortunately, the same could almost have been said for the United States. In theory, with no organized opposition, all Scott’s army had to do was march the two hundred miles to Mexico City. Moving actual troops, however, was a lot more complicated than shifting pins on a map. More than a thousand men in Scott’s command were on the sick list, and yellow fever threatened to strike many others with the arrival of warm weather. Meanwhile, the supply effort was hobbled by shortages of mules, teamsters, wagons, and money.

In addition, seven volunteer regiments were set to go home in May and June, when their twelve-month terms expired. Officers appealed to the men to re-enlist, but most had gotten their fill of military glory and did not look forward to a Mexican summer. Scott knew that any delay would allow the resourceful Santa Anna to organize a defense of Mexico City, yet he had no choice. After bloodlessly occupying Puebla, Mexico’s second-largest city, on May 15, the remnants of his army settled in for three months to recuperate, await reinforcements, and firm up supply lines.

As they paused from fighting the Mexicans, Scott and his fellow Americans enthusiastically continued fighting one another. The general was a Whig with political ambitions, while President James K. Polk was a Democrat, so each faced the difficult task of winning the war without letting the other claim any credit. Their combat had intensified on April 15, when Polk dispatched Nicholas Trist to negotiate a peace treaty. While Trist’s credentials identified him as “second in rank in the American department of foreign affairs,” Scott more accurately dismissed him as “chief clerk.” With few demonstrated abilities beyond a talent for making influential friends, Trist had apparently been chosen for the mission because he spoke Spanish.

After Trist’s arrival in Mexico, he and the general passed the time exchanging snide notes and whining to their superiors in Washington. Polk complained