Port-Toulouse was an Acadian village situated in the French colony of Île-Royale, which is now Cape Breton Island. It was located on the present site of the Nova Scotian village of St. Peter's, on the strait that separates Bras d'Or Lake from the Atlantic Ocean.
After the Treaty of Utrecht (1713) when continental Acadia was ceded to Great Britain, France encouraged settlement by the Acadians on Île Royale, which was still in French possession. Port-Toulouse was thus founded in 1715 by Acadians from Plaisance and Grand-Pré, which was established near an old trading port founded in 1630 by merchants from La Rochelle and fortified by Nicolas Denys. Due to the strategic importance of the area, the French constructed a fort on the shoreline to protect Port-Toulouse, which became the logistical port and naval base for Louisbourg, situated 120 kilometres (75 mi) to the north.