Complex sentence: In addition, Arteaga continued to believe he faced only 2,500 Peruvian soldiers when in fact Arteaga's forces added up to just 2,281 men, around half the strength of Buendía's contingent.
Split into simpler sentences: In addition, Arteaga continued to believe he faced only 2,500 Peruvian soldiers. In fact, Arteaga's forces added up 2,281 men, only half the strength of Buendía's contingent.