August 18, 1661: King Okai Koi of the Gas signs a treaty with Denmark for a permanent trading post- Fort Christiansborg

The area around present day Osu, came under the control of Sweden in the 1650s, led by the a Dutch trader Henry Caerlof. In 1652, he was given permission to build a small fortified lodge by the King of Accra, with whom he had previously done business. In 1660, control passed to the Netherlands but it was soon lost to Denmark-Norway. In 1657, Caerlof had again traveled to West Africa, this time representing Denmark-Norway.  On August 18 1661, Jost Cramer, Danish governor of Fredericksborg, near Cape Coast, acquired land from Chief Okai Koi for 3,200 gold florins. The Danes built a stone fort to replace the earthen lodge and named it Christiansborg (Christian’s fortress) after the former King of Denmark, Christian IV who had died in 1648. In its early years it was a seat of trade in gold and ivory but by the 17th century slave trading had become the core business as it was, all over the coast of West Africa.

The fort was controlled at different times by the Danes, the Akwamus and later the British, who purchased all the Danish possessions for £10,000 in 1850. It later became the seat of the British Colonial government when the capital was moved from Cape Coast to Accra.