success. The operations costs 15 to 20 million guilders a year, which nearly bankrupted the colonial government. First Dutch offensive In 1873, negotiations took place in Singapore between representatives of the Aceh Sultanate and the local American Consul over a potential bilateral treaty. The Dutch saw this as a violation of a prior agreement with the British in 1871 and used this as an opportunity to annex Aceh militarily. An expedition under Major General Johan Harmen Rudolf Köhler was sent out on 26 March 1873, which bombarded the capital Banda Aceh and was able to occupy most of the coastal areas by April. It was the intention of the Dutch to attack and take the Sultan's palace, which would also lead to the occupation of the entire country. The Sultan requested and possibly received military aid from Italy and the United Kingdom in Singapore. In any case the Aceh army was rapidly modernised and enlarged with figures ranging from 10,000 to 100,000. Underestimating the military abilities of the Acehnese, the Dutch made some tactical errors and sustained losses including the deaths of Köhler and 80 troops. These defeats undermined Dutch morale and prestige. Forced to retreat, the Dutch imposed a naval blockade of Aceh. In an attempt to preserve Aceh's independence, Sultan Mahmud appealed to the other Western powers and Turkey for direct help but to little avail. While the American Consul was sympathetic, the American government remained neutral. Due to its weak position in the international political stage, the Ottoman Empire was impotent and the British refused to intervene due to their relations with the Dutch. Only the French agreed to respond to Mahmud's appeal. Second Dutch offensive In November 1873, a second expedition consisting of 13,000 troops led by General Jan van Swieten was dispatched to Aceh. The invasion coincided with a cholera outbreak which killed thousands on both sides. By January 1874, deteriorating conditions forced Sultan Mahmud Syah and his followers to abandon Banda Aceh and retreat to the interior. Meanwhile, Dutch forces occupied the capital and captured the symbolically important dalam (sultan's palace), leading the Dutch to believe that they had won. The Dutch occupiers then abolished the Acehnese Sultanate and declared Aceh to be annexed to the Dutch East Indies proper. Following Mahmud's death from cholera, the Acehnese proclaimed a young grandson of Alauddin Ibrahim Mansur Syah, named Tuanku Muhammad Daud, as Alauddin Muhammad Da'ud