Fort Dauphin was the most durable French settlement in Madagascar, at the modern site of Tôlanaro, before the 19th century.
It was founded in 1643 by the French East India Company and named in honor of the crown prince of France, the future Louis XIV. It was settled by around a hundred colonists, who found themselves involved in the local politics. The poor trade results (some ebony and little more was obtained) hardly justified the difficulties of the settlers, who suffered from tropical illnesses and other problems. After a conflict with the Antanosy people, the survivors were evacuated in 1674.
One temporary settler of this colony, Ettiene de Flacourt, published, back in France, the History of the Great Isle of Madagascar and Relations, that was the main source of information on the island for Europeans until the late 19th century.
Journeys trips that include Fort Dauphin:
Information based on http://en.wikipedia.org/wiki/Fort_Dauphin_%28Madagascar%29