On the second day of fighting, unexpected cannon fire shattered the midday silence in tangled thickets beside the ravine, where hundreds of Mexican soldiers had been resting in the shade and preparing to eat their first meal in 24 hours. The Army of the North had marched five miles since sunrise and redeployed into battle lines there. The weary men of the Tampico Battalion took up their muskets and bayonets and reformed their lines to face another battle. Cannon fire at Palo Alto the day before had already inflicted heavy losses on this unit, which both armies respected for its hard-bitten valor. The Tampico Guarda Costa, regarded as the best regiment in the Mexican service, did not retreat but fell at their posts, and most of their officers and men were killed or captured. Since before the empire of the Aztecs, armies in Mexico had traditionally been accompanied by large groups of women called soldaderas, and mass graves found at Resaca de la Palma contained the remains of Mexican women killed in the thick of the fighting there.