After defeating the Philippine Republic’s conventional forces in 1899, the U.S. Army was broken up into small garrisons to prepare Luzon for colonial rule. The Filipino nationalists transformed their resistance into a guerrilla warfare that varied so greatly from region to region in its organization, strategy, and tactics that early American attempts at centralization and nonmilitary pacification were useless. The study offers new insights for counterinsurgency theory and for the study of America’s military experience in Asia.