Acehnese War, (1873–1904), an armed conflict between the Netherlands and the Muslim sultanate of Aceh (also spelled Acheh, or Atjeh) in northern Sumatra that resulted in Dutch conquest of the Acehnese and, ultimately, in Dutch domination of the entire region. In 1871 the Netherlands and Britain had signed a treaty that recognized Dutch influence in northern Sumatra in return for Dutch confirmation of Britain’s right of equal trade in the East Indies.
The Dutch, considering Aceh as within their sphere of influence, decided to conquer the area and sent two expeditions to Aceh in 1873. The palace was seized and shortly afterward the Acehnese sultan died. The Dutch suspended military operations and concluded a treaty with the new sultan, who recognized Dutch sovereignty over the area. He was unable to control his subjects, however, and Dutch forces became involved in a prolonged guerrilla war in the countryside. This war, however, drained the colonial treasury, and public opinion in the Netherlands became increasingly critical of the colonial administration.
The administration later realized that their ignorance of the region had led them to commit serious errors. Christiaan Snouck Hurgronje, professor of Islamic studies at the University of Leyden (Leiden), was invited to undertake a thorough study of Aceh and published a book in 1893–94 on the Acehnese. A “castle strategy,” which provided fortified bases for the Dutch troops, was then introduced. Under the leadership of J.B. van Heutsz, who was appointed military and civil governor of Aceh in 1899, the kingdom was quickly subdued. The conquest of the entire region was accomplished by van Heutsz in 1904.