 In 1658, Kettler was made a prisoner by the Swedes during a war between Sweden and Poland.As a consequence, funds were no longer available to maintain the garrisons and settlements in the Gambia and in 1659, the Duke of Courland's agent at Amsterdam entered into an agreement with the Dutch West India Company whereby the Duke's possessions in the Gambia were handed over to the company.In 1660, the fort on St Andrew's Island was captured and plundered by a French privateer in Swedish service.The Dutch thereafter abandoned the fort and the Courlanders resumed possession.