After Sweden permanently broke away from the personal union, Denmark tried on several occasions to reassert control over its neighbour. King Christian IV attacked Sweden in the 1611–1613 Kalmar War but failed to accomplish his main objective of forcing it to return to the union. The war led to no territorial changes, but Sweden was forced to pay a war indemnity of 1 million silver riksdaler to Denmark, an amount known as the ''Älvsborg ransom''. King Christian used this money to found several towns and fortresses, most notably Glückstadt (founded as a rival to Hamburg) and Christiania. Inspired by the Dutch East India Company, he founded a similar Danish company and planned to claim Ceylon as a colony, but the company only managed to acquire Tranquebar on India's Coromandel Coast. Denmark's large colonial aspirations included a few key trading posts in Africa and India. While Denmark's trading posts in India were of little note, it played an important role in the highly lucrative transatlantic slave trade, through its trading outposts in Fort Christiansborg in Osu, Ghana though which 1.5 million slaves were traded. While the Danish colonial empire was sustained by trade with other major powers, and plantations – ultimately a lack of resources led to its stagnation.