The Great Upheaval, also known as the Great Expulsion, The Deportation, the Acadian Expulsion, or to the deportees, Le Grand Dérangement, was the forced population transfer of the Acadian population from Nova Scotia between 1755 and 1763, ordered by British governor Charles Lawrence and the Nova Scotia Council.

The relationship between the French and British colonists in Nova Scotia had long been one filled with animosity. Though the French initially colonised the area, various treaties traded possession of the region between the English/British, and French through the 1600s and beyond. The Treaty of Utrecht in 1713 saw the territory of Acadia definitively ceded to the British. The Acadians were forced to swear an oath in 1730 giving their allegiance to the British crown but with a caveat that they would not be required to bear arms against the French or First Nations. Richard Phillips, the British governor at the time, was said to have verbally approved of this arrangement.

Despite this agreement, British distrust of the Acadian settlers remained. Successive governors continued to pressure the Acadians to firmly state where their loyalties lay but it would not become a pressing concern for the British until 1755. That year, the British attacked the French Fort Beauséjour during the beginnings of a major military offensive to gain greater control of the continent. Within the walls of the fort, 300 Acadians were found . Despite claims that they had been forced to take up arms against their will, the discovery completely eroded British trust of the Acadians.

Governor Lawrence gave the Acadians one last opportunity to swear allegiance to the British Crown. The Acadians again refused, believing that this demand was no different than ones made over the past few decades.

The British response was swift and unforgiving. Before 1755 was over, an estimated 6,000 Acadians - approximately three-quarters of their total population - were rounded up as prisoners and forced onto ships bound for the British American colonies, Europe, and British prisons. Nearly half would die en route. By 1763, over 10,000 Acadians had been deported from the Maritimes. Some were shipped as far as the Falkland Islands. The largest single group was returned to France where it was poorly treated and ostracized by French society .