Sackville, town (1991 pop. 5,494), SE N.B., Canada, near the head of Chignecto Bay, an arm of the Bay of Fundy. The early French Acadian settlers diked and reclaimed the nearby Tantramar marshes, creating fertile agricultural land. The first Baptist church in Canada was established there in the 1770s. Sackville is the seat of Mt. Allison Univ.