March, 1847 - April, 1847
With the fall of Vera Cruz in March, 1847, Scott decided to move his force into the interior before the onset of the yellow fever season. In April the army began its march into the highlands, en route to the Mexican capital. During the next six weeks Scott's army would secure all the major towns along the National Road from Puebla to the coast. Mexican guerillas would harass U.S. supply trains for the remainder of the war.