The fact that a Moro fort at Mamburao threatened Manila, the capital of the colonial government, embarrassed the conquerors in the eyes of their native subjects, which was politically intolerable to the Spanish administrators. So in 1766, the Spaniards gathered a large force of 1,200 marines, augmented by a large army of native mercenaries, and burned the Iranun fort. But the Moros simply faded into the hills to escape, and came back when the counter-raid was over and the raiders returned to Manila.