In 1775 at the start of the American Revolution, rebel forces invaded Canada, occupying Montréal and attacking the town of Québec. American privateers also raided Atlantic ports, and revolutionary sympathizers in Nova Scotia attempted a rebellion in that colony. Although the rebel forces were defeated in Canada, the 13 American colonies won their war for independence from Britain, sparking another kind of invasion – a wave of Loyalist emigration that would change the make-up of Canada.

Québec Act

In the late 18th Century, disputes over taxes and other matters of colonial administration in the 13 American colonies had created a simmering dissatisfaction with British imperial rule. The passing by the British Parliament of the Quebec Act in 1774 led to further anger. The Act guaranteed religious freedom for Roman Catholics and restored French civil law in the conquered colony of Québec – raising the ire of anti-Catholic American Protestants. The Act also greatly enlarged Québec's territory to include, among other areas, the unsettled lands of the Ohio valley. This constrained the desires of Americans such as future rebel leader George Washington, to expand the American colonies westward. These frustrations broke into open war between United States rebels and British forces at Lexington, Massachusetts on 18 April 1775.The American rebels mounted a propaganda campaign for support in what is now Canada. They attracted some sympathy inside Québec particularly in Montréal, where there was some pro-American activity. Officially, however, the French Canadian clergy, land owners and leading citizens adopted a policy of support for the British, and otherwise most of the common people in the Canadian and Maritime colonies remained neutral and reluctant to become involved in the Revolution to the south. Canadian Governor Sir Guy Carleton (Lord Dorchester) also had little success in raising a militia to help counter the American rebels.

Invasion of Québec

In September 1775 rebel General Richard Montgomery led American forces on the first major offensive of the war, seizing the forts at Ticonderoga and Crown Point in northern New York, and Fort Chambly in Québec. With 1,700 militia troops, Montgomery then captured Fort Saint-Jean outside Montréal in November – prompting Carleton to abandon Montréal and flee to Québec. The Americans occupied Montréal without a fight on 28 November.

Meanwhile, a second American invasion force led by General Benedict Arnold managed, despite hardships, faulty maps, near starvation and desertions, to bring about 700 men through the Maine wilderness to the St. Lawrence River and to the fortress of Québec. Arnold waited outside Québec until December, when Montgomery joined him with 300 additional men.

During a snowstorm on 31 December, the Americans assaulted Québec, which was defended by a garrison of 1,800 British soldiers and militiamen under Carleton. The Americans attacked from two directions. Arnold and his men penetrated some distance into Lower Town, but Arnold himself was wounded in the ankle and carried away from the fighting. His forces later surrendered under counterattack.

Montgomery's force was repulsed after the general and his leading officers were killed by rifle fire in their initial assault on the other side of Lower Town. In total, 60 Americans were killed and 426 wounded at Québec. On the British side six were killed and 19 wounded.

Siege and Retreat

Under Arnold's command, the remaining uncaptured Americans tried to maintain a siege of the town through the winter, but it was ineffective. The group was easily routed when the spring thaw brought 4,000 British troop reinforcements led by British General John Burgoyne. The Americans abandoned Montréal on 9 May, 1776 and the remains of the force was defeated at Trois Rivieres in June. The survivors then retreated to New York, ending their invasion.

The American invasion left bitter memories among Canadians, and drove many American sympathizers into exile from Québec. However, there had been little active support for the American rebels: clergy and land owners remained staunchly loyal to the Crown and, after some delay in choosing sides, so did the merchant class – many of whom had shared the American resentment at having to pay taxes to Britain.

The American invaders had expected French Canadians to pick up arms against the British and fight alongside them, but they badly misjudged Canadian sentiment. Most ordinary habitants remained determinedly neutral – refusing to take up arms against either their British rulers, or the American rebels.

Burgoyne and his British soldiers pursued the retreating Americans out of Canada, leading a counter-invasion southward via Lake Champlain in New York. Burgoyne, however, overextended himself. In the first great American victory of the Revolutionary war, Burgoyne's force was defeated and surrendered at Saratoga on 17 October 1777.

Rebel Actions in Nova Scotia

As in previous conflicts such as the Seven Years War, Nova Scotia remained an uncertain battleground during the Revolution, thanks in part to its French Acadian population. The provincial Assembly in Halifax voted in favour of loyalty to the Crown, but illegal town meetings gave secret support to the rebels in New England.

Nearly every important coastal outpost outside Halifax suffered from American privateering. In 1776, a force of New England rebels and disaffected Nova Scotians – hoping to launch a rebellion and seize the entire colony – made a futile attack on Fort Cumberland (Fort Beauséjour). The Fort's garrison held out until British troops arrived from Halifax, defeating the attackers and crushing the rebellion.

Loyalist Legacy

Despite the American rebels' failed efforts to bring their revolution to Nova Scotia and Canada, they did win their war against Britain in the 13 colonies. Prominent American colonists signed the Declaration of Independence on 4 July 1776. After a protracted struggle, British forces surrendered in October 1781. Two years later the Treaty of Paris formally recognized the United States of America.

The main consequence for the British colonies to the north was the emergence of a republican state – a powerful, continental neighbour of whom Canadians, Maritimers and their colonial rulers would remain suspicious for decades to come.

The Revolution also triggered the exodus of more than 80,000 Loyalist refugees out of the United States, about half of whom migrated into Québec and the Maritimes. Loyalist settlement greatly influenced the politics and culture of what would eventually become the nation of Canada, and determined that its development would differ profoundly from the United States (see Canada and the United States).