Britain and the Netherlands signed the Sumatra Treaty, which recognized expanded Dutch influence in Sumatra in exchange for trade guarantees. This reduced the chances that another European power would protect Aceh and helped set the stage for Dutch military action.
Dutch forces began a major assault on Aceh, including bombardment and landings near the Acehnese capital area. The campaign failed to break Acehnese resistance, and Dutch commander J.H.R. Köhler was killed, undermining Dutch expectations of a quick victory.
After withdrawing from their initial push, the Dutch shifted to a blockade strategy to pressure Aceh and limit weapons and supplies. This escalation widened the conflict and made a long war more likely, as Acehnese leaders continued organizing resistance.
A much larger Dutch force landed and fought its way into the capital area amid severe disease outbreaks, especially cholera. The Dutch occupied key sites and believed they had effectively ended the war, but Acehnese fighters withdrew inland and continued guerrilla warfare.
After taking the capital area, the Dutch proclaimed Aceh annexed into the Dutch East Indies and treated the sultanate as dissolved. This turned a military campaign into an open-ended colonial conquest, intensifying Acehnese resistance rather than ending it.
Aceh’s sultan, Alauddin Mahmud Syah II, died of cholera during the crisis following the Dutch capture of the capital area. His death removed a central figure at a key moment, but it did not end Acehnese political and religious leadership of resistance.
The Dutch formed an elite colonial gendarmerie (military police) unit to fight the war more effectively. Its smaller, mobile patrols were designed for jungle and village warfare, supporting a shift from large expeditions to sustained counter-guerrilla operations.
Teungku Chik di Tiro, a major religious leader who helped organize armed resistance, died in 1891. His death was a turning point: it disrupted one resistance network while other leaders and local commanders continued the fight in different regions.
Islamic scholar Christiaan Snouck Hurgronje published detailed studies of Acehnese society and politics in 1893–1894. Dutch officials used his work to refine strategy—especially by separating religious leaders from local aristocrats and building control through selective alliances.
Acehnese commander Teuku Umar surrendered to the Dutch and was accepted into their ranks, gaining access to weapons and supplies. He later left with men and equipment to rejoin the Acehnese struggle, demonstrating how shifting alliances shaped the war’s course.
J.B. van Heutsz was appointed military and civil governor of Aceh, bringing together civilian administration and military command. Using more mobile units and intelligence-driven tactics, he accelerated Dutch operations against remaining resistance centers.
In 1903, major Acehnese leaders—including the symbolic sultan—capitulated to the Dutch. While not ending all fighting, these surrenders weakened centralized resistance and allowed the Dutch to expand administrative control more widely.
During Dutch operations in the Gayo and Alas highlands, KNIL forces attacked the fortified village of Kuta Reh and killed most inhabitants. Photographs and reports from this period became lasting evidence of extreme violence used in the final “pacification” campaigns.
By 1904, the Dutch declared the war effectively over and treated Aceh as subdued, even though scattered resistance continued for years. The end of the formal Aceh War marked a major step in bringing the outer islands under direct Dutch colonial rule.
Aceh War and Dutch pacification of Aceh (1873–1904)