In 1756 Bougainville was stationed in Canada as captain of dragoons and aide-de-camp to the Marquis de Montcalm.
He took an active part in the capture of Fort Oswego in 1756 and the 1757 Battle of Fort William Henry.
He was wounded in 1758 at the successful defence of Fort Carillon.
He sailed back to France the following winter, under orders from the marquis to obtain additional military resources for the colony.
During this crossing, he continued to learn about the ways of the sea, skills that would later serve him well.
Having distinguished himself in the war against Britain, Bougainville was rewarded with the Cross of St Louis and promoted to colonel.
When he returned to Canada the following year, he had gained few supplies.
The metropolitan officials had decided that, "When the house is on fire, one does not worry about the stables".

During the pivotal year of 1759 (see Seven Years' War and French and Indian War), Bougainville participated in the defence of fortified Quebec, the capital of New France.
With a small elite troop under his command, among which were the Grenadiers and the Volontaires à cheval, he patrolled the north shore of the St. Lawrence River, upstream from the city; he prevented the British several times from landing and cutting communications with Montreal.
He did not have sufficient time, however, to rally his troops and attack the British rear when they successfully ascended the Plains of Abraham and attacked Quebec on 13 September.

Following the death of the Marquis de Montcalm and the fall of Québec on 18 September – after the colonel's aborted attempt to resupply the besieged city – Bougainville was dispatched to the western front by his new commanding officer, the Chevalier de Lévis.
He attempted to stop the three pronged attack against Montréal from his entrenchments at Île-aux-Noix.
He was among the officers who accompanied Lévis to Saint Helen's Island off Montreal for the last French stand in North America before the general capitulation of 1761.
Of the war, Bougainville wrote in his journal: "It is an abominable kind of war.
The very air we breathe is contagious of insensibility and hardness".

Shipped back to Europe along with the other French officers, all deprived of military honours by the victors, Bougainville was prohibited by the terms of surrender from any further active duty against the British.
He spent the remaining years of the Seven Years' War (1761 to 1763) as a diplomat, helping to negotiate the Treaty of Paris.
Under this France ceded most of New France east of the Mississippi River to the British Empire.
In 1756 Bougainville was stationed in Canada as captain of dragoons and aide-de-camp to the Marquis de Montcalm. He took an active part in the capture of Fort Oswego in 1756 and the 1757 Battle of Fort William Henry. He was wounded in 1758 at the successful defence of Fort Carillon. He sailed back to France the following winter, under orders from the marquis to obtain additional military resources for the colony. During this crossing, he continued to learn about the ways of the sea, skills that would later serve him well. Having distinguished himself in the war against Britain, Bougainville was rewarded with the Cross of St Louis and promoted to colonel. When he returned to Canada the following year, he had gained few supplies. The metropolitan officials had decided that, "When the house is on fire, one does not worry about the stables".
During the pivotal year of 1759 (see Seven Years' War and French and Indian War), Bougainville participated in the defence of fortified Quebec, the capital of New France. With a small elite troop under his command, among which were the Grenadiers and the Volontaires à cheval, he patrolled the north shore of the St. Lawrence River, upstream from the city; he prevented the British several times from landing and cutting communications with Montreal. He did not have sufficient time, however, to rally his troops and attack the British rear when they successfully ascended the Plains of Abraham and attacked Quebec on 13 September.
Following the death of the Marquis de Montcalm and the fall of Québec on 18 September – after the colonel's aborted attempt to resupply the besieged city – Bougainville was dispatched to the western front by his new commanding officer, the Chevalier de Lévis. He attempted to stop the three pronged attack against Montréal from his entrenchments at Île-aux-Noix. He was among the officers who accompanied Lévis to Saint Helen's Island off Montreal for the last French stand in North America before the general capitulation of 1761. Of the war, Bougainville wrote in his journal: "It is an abominable kind of war. The very air we breathe is contagious of insensibility and hardness".
Shipped back to Europe along with the other French officers, all deprived of military honours by the victors, Bougainville was prohibited by the terms of surrender from any further active duty against the British. He spent the remaining years of the Seven Years' War (1761 to 1763) as a diplomat, helping to negotiate the Treaty of Paris. Under this France ceded most of New France east of the Mississippi River to the British Empire.
Louis Antoine de Bougainville