The Acadians were victims of the long conflict between the United Kingdom and France which sputtered off and on throughout the 18th century.
From the mid-1500's, various small French settlements were founded and failed. Although the bitterly cold weather in the northern reaches of the continent formed the greatest challenge to settlement, even in warmer southern areas like Florida colonies failed due to the sheer unpredictability of the challenges. Europeans had been living in France for thousands of years, and knew the plants and animals they could eat, as well as what types of wildlife might be dangerous and how to deal with them. In North America, not only was the plantlife quite different, there were many different species of large and dangerous wildlife such as cougars, alligators, grizzly bears and wolves, all of which could be dangerous to humans.
The settlement of Acadia is usually dated from 1604, when a colony was established on a small island near the mouth of the St. Croix river. The location proved to be less than ideal, as the island was relatively small and exposed to very harsh winter weather. After a difficult winter during which many settlers died of malnutrtion and scurvy, the colony relocated from the small island to the mainland, founding Port Royal in what would become the Canadian province of Nova Scotia. The colony did much better in the relatively fertile and benign climate of the Annapolis valley. However, in 1613 the long series of English attacks and French reprisals got underway with the destruction of Port Royal by English raiders out of Jamestown, Virginia. Over the next hundred years, Acadia would change hands several times as the fortunes of war in Europe ebbed and flowed.
The Treaty of Utrecht in 1713 ceded Acadia to Britain for the last time. The British took a relatively "hands-off" approach to their Acadian subjects, allowing them to live in peace, speaking their dialect of French and worshiping as Roman Catholics. The Acadians tended to keep to themselves, and took an oath of loyalty to the British crown in 1730 which stipulated that they would remain neutral in any conflict between Britain and either the French or the native population, with whom they had a long history of peaceful cooperation.
At the start of the 1754 French and Indian War, the Governor of Nova Scotia no longer believed the Acadians could be relied upon to remain neutral, and demanded a new oath of loyalty which might require them to fight against France. Most Acadians refused, and Governor Lawrence signed the order to deport them from the colony. The summer and fall of 1755 saw 6000 Acadians forcibly deported from the colony, their homes and farms destroyed, and in come cases families torn apart and sent to different locations. The Thirteen Colonies absorbed most of the deportees, while others were sent to England, Quebec or even, in the end, France. Around 75% of the Acadian population of the colony was forcibly removed, while others fled north or east to resettle. Another 3000 or so Acadians were expelled and sent to France when Louisbourg, the French possession in what would later become Cape Breton Island, was captured.
At the end of the Seven Years war in 1763, the Acadians were officially permitted to return as long as they did not settle near Port Royal or too many in one location. However, by this point many Acadians had given up on their old home, and resettled elsewhere for good. A large number of Acadians settled in what was then the Spanish possession of Louisiana, becoming the Cajuns.
There has been much debate as to whether the Acadians bear some responsibility for their own misfortune by refusing to take a second oath of loyalty to the crown. However, even at the time, the expulsion was widely seen as a very harsh action. Today, the expulsion of the Acadians is seen as a shameful episode in North American history, and a great and unwarranted injustice against an entire people.