The Fortress Of Louisbourg In all of North America, you will not find a more power fortress than Louisbourg. It was said to be indestructible, but was proven otherwise on a number of occasions. Established in 1713 and located on Northern Cape Breton Island, Louisbourg was not only a fortress but a major commercial center as well. Louisbourg was originally known as Port St. Louis, and its main purpose was protecting Quebec and Montreal by guarding the entrance to the St. Lawrence River against hostile ships. The other main job for Louisbourg was serving as a base for the cod fishing industry. French fishing ships could come to