Complex sentence: After the fall of Louisbourg, the resident French population of Île Royal (present-day Cape Breton Island) were deported to France while the Acadians of Île Saint-Jean lived under the threat of deportation for the remainder of the war.
Split into simpler sentences: After the fall of Louisbourg, the resident French population of Ile Royal were deported to France. The Acadians of Ile Saint-Jean lived under the threat of deportation for the remainder of the war.