 Aulac is situated upon the Aulac Ridge, a prominent rise running west–east across the Tantramar Marshes on the Isthmus of Chignecto, approximately 2 kilometres west of the Missaguash River which forms the southern part of the inter-provincial boundary with Nova Scotia.Aulac became strategically important for French military forces during the 18th century after ceding what is now peninsular Nova Scotia to Britain in the 1713 Treaty of Utrecht; the words describing the boundary of Acadia (then including all of Nova Scotia, New Brunswick, Cape Breton Island, Prince Edward Island, the Gaspé Peninsula, Anticosti Island and part of eastern Maine) were sufficiently vague as to permit France to establish the Missaguash River as the boundary between Britain's new colony and New France.During Father Le Loutre's War, British military forces constructed a log stockade on the Fort Lawrence Ridge, 3 km to the south of Aulac, naming their facility Fort Lawrence, which was promptly answered by the French construction of Fort Beauséjour at the western end of the Aulac Ridge, overlooking the Cumberland Basin of the Bay of Fundy.