The Great Upheaval (le Grand Dérangement), also known as the Great Expulsion or the Acadian Expulsion, is the eviction of the Acadian population from Nova Scotia between 1755 and 1763, ordered by governor Charles Lawrence and the Nova Scotia Council. It can be seen as an ethnic cleansing.

Though the French initially colonised the area, various treaties traded possession of the region between the British and French through the 1600s and beyond. The Treaty of Utrecht in 1713 cemented the Acadians as British subjects. They were forced to swear an oath in 1730 giving their allegiance to the British crown but with a caveat that they would not be forced to bear arms against the French or Indians. In 1754, the French and Indian War broke out and the Acadians were being forced to remove the caveat of fighting the French from their previous oath. The majority of Acadians refused.

Thousands of the French-speaking inhabitants were gathered together on ships and sent south, with some congregating in Cajun Louisiana, at the encouragement of the King of France. The homes and farms around the Bay of Fundy were burned or given to English-speaking Protestant colonists. For example, on 4 June 1760 New England planters arrived to claim land in Nova Scotia taken from the Acadians.

The following table presents figures on the deportation of the Acadians:

Table source: R.A. LEBLANC. Les migrations acadiennes, in Cahiers de géographie du Québec, vol. 23, no 58, april 1979, p. 99-124.

The deportation was commemorated in 1847 by Henry Wadsworth Longfellow in his poem Evangeline. In December 2003, Governor General Adrienne Clarkson, representing Canada's head of state, declared the Crown's acknowledgement (but without an apology) of the event and designated July 28 as "A Day of Commemoration of the Great Upheaval."