Siege of Louisbourg may refer to: Siege of Louisbourg (1745), the capture of the settlement by British forces during the War of the Austrian Succession Siege of Louisbourg (1758), the capture of the settlement by British forces during the Seven Years' War, after which it was permanently ceded to the British See also Louisbourg Expedition Louisbourg Expedition (1757), a cancelled British plan to capture Louisbourg during the Seven Years' War Duc d'Anville Expedition (1746), a failed French attempt to capture Louisbourg