Complex sentence: Poor Mexican leadership allowed the Americans to avert disaster, and, after some intense urban fighting, General Ampudia was compelled to offer Taylor an eight-week ceasefire highly favorable to the Mexicans.
Split into simpler sentences: Poor Mexican leadership allowed the Americans to avert disaster, and, after some intense urban fighting, General Ampudia was compelled to offer a truce. Taylor accepted an eight-week ceasefire under terms that were highly favorable to the Mexicans.