Curonian colonisation was the colonisation efforts of the Duchy of Courland and Semigallia (today part of Latvia), a vassal duchy of the Polish–Lithuanian Commonwealth. Small, but wealthy, the Duchy took a modest part in the European colonization settlement attempts of West Africa and the Caribbean.

In 1651, Courland and Semigallia leased a colony in Africa on St. Andrew's Island in the Gambia River from the Kingdom of Niumi[1] and went on to build Fort Jakob on the island. The Duchy also leased St. Mary Island (modern-day Banjul) from Kombo and Fort Jillifree from Niumi. The Courland and Semigallia's colonies exported sugar, tobacco, coffee, cotton, ginger, indigo, rum, cocoa, tortoise shells, as well as tropical birds and their much sought after feathers. In the end, the Duchy would manage to retain control of these lands for less than a decade and the colonies were formally ceded to England in 1664.

The colonies were lost when Courland and Semigallia's neighbours took advantage of its weakened defences during the Northern Wars, when Jakob was held captive by the Swedish Army from 1658 to 1660. After the end of the war, the island of Tobago was returned to Courland. However, the Duchy ended up abandoning the island in 1666. In 1668, a Curonian ship attempted to reoccupy Fort Jacob but was driven off by the Dutch garrison stationed on the island. The Courland Monument near Great Courland Bay commemorates the Duchy's settlements.

St. Andrews Island or Courlander Gambia was also the later British Fort James. (1651–1660, 1660–1661)

New Courland, on Tobago (1637, 1642, 1654–1659, 1680–1690)

It's always the ones you least expect.