Uspantek activity became sufficiently troublesome that the Spanish decided that military action was necessary. Gaspar Arias, the magistrate of Guatemala, penetrated the eastern Cuchumatanes with 60 Spanish infantry and 300 allied indigenous warriors. By early September he had imposed temporary Spanish authority over the Ixil towns of Chajul and Nebaj. The Spanish army then marched east toward Uspantán itself; Arias then received notice that the acting governor of Guatemala, Francisco de Orduña, had deposed him as a magistrate. Arias handed command over to the inexperienced Pedro de Olmos and returned to confront de Orduña. Although his officers advised against it, Olmos launched a disastrous full-scale frontal assault on the city. As soon as the Spanish began their assault they were ambushed from the rear by more than 2,000 Uspantek warriors. The Spanish forces were routed with heavy losses; many of their indigenous allies were slain, and many more were captured alive by the Uspantek warriors only to be sacrificed on the altar of their deity Exbalamquen. The survivors who managed to evade capture fought their way back to the Spanish garrison at Q'umarkaj.