LOUISBURG, a town and port of entry of Cape Breton county, Nova Scotia, Canada, on the Sydney & Louisburg railway, 39 m. from Sydney.Under the French regime, Louisburg was second only to Quebec. A fortress was erected at enormous expense, and the city was the centre of the cod-fisheries. The fortress was, however, captured in 1745 by the American colonists, under Sir William Pepperrell (1696-1759), assisted by the British fleet, and again in 1758 by a British land and sea force under General Jeffrey Amherst (1717-1797) and Admiral Boscawen. The jealousy of the British settlement of Halifax led to its almost utter destruction, and only a few casemates now remain. Under English rule a fishing village grew up on the other side of the harbour, and has now become the winter shipping port of the Dominion Coal Company. The harbour is deep, spacious and open all the year round, though occasionally blocked by drift ice in the spring.