For most of the colonial period, Dutch control over the archipelago was tenuous. Dutch forces were engaged continuously in quelling rebellions both on and off Java. The influence of local leaders such as Prince Diponegoro in central Java, Imam Bonjol in central Sumatra, Pattimura in Maluku, and the bloody 30-year war in Aceh weakened the Dutch and tied up the colonial military forces. Only in the early 20th century did Dutch dominance extend to what was to become Indonesia's current boundaries.