May, 1847 - August, 1847
After his victory at Cerro Gordo, Scott took Jalapa, then moved his army up the National Road to Puebla in mid-May. Although now only 75 miles from the capital, the U.S. drive suddenly and unexpectedly stalled. The war legislation under which U.S. volunteers had enlisted required them to serve 12 months or the duration of the conflict. After almost 11 months of service, many had had their fill of war and were anxious to go home. Unable to persuade his troops to extend their terms of enlistment, Scott allowed 3,000 volunteers to withdraw immediately.
For the next ten weeks, Scott remained at Puebla while awaiting reinforcements. The army fought boredom and disease while Mexican guerrillas harassed his supply trains coming up from Vera Cruz.
Though Scott was frustrated by his inability to march on the capital and end the war, Mexican leaders were unable to take advantage of the situation, being more deeply divided in the wake of the disaster at Cerro Gordo than ever before. With liberal federalists calling for a negotiated settlement and a bellicose war faction calling on Mexicans to mount a heroic defense of the capital, a consensus in the Mexican Congress became impossible. Thus Santa Anna remained in power, a dictator by default.