The Aceh War (also Achinese War) took place from 1873-1904 between the Netherlands and the people of Aceh in Sumatra as the Dutch attempted to colonize this independent state on the northern-most tip of Sumatra.
This war was the most costly colonial war ever fought by the Dutch. Before this, the Dutch had been trying to colonize Aceh for the last four hundred years without much success.
The Dutch colonial government declared war on Aceh on 26 March 1873; the apparent immediate trigger for their invasion was discussions between representatives of Aceh and the United States in Singapore during early 1873.
Around 1880 the Dutch strategy changed, and rather than continuing the war, they now concentrated on defending areas they already controlled, which were mostly limited to the capital city (modern Banda Aceh), and the harbour town of Ulee Lheue.
War began again in 1883, when the British ship Nisero was stranded in Aceh, in an area where the Dutch had little influence.