The French and Indian War, known in Europe as the Seven Years War, begins in earnest in 1756.

At the start of the war, no French regular army troops are stationed in North America, and few British troops.

New France is defended by about three thousand troupes de la marine, companies of colonial regulars (some of whom have significant woodland combat experience).

The colonial government recruits militia support when needed.

Most British colonies muster local militia companies, generally ill trained and available only for short periods, to deal with native threats, but do not have any standing forces.

Virginia, because of its large frontier, has several companies of British regulars.

The colonial governments are used to operating independently of each other and of the government in London, a situation that complicates negotiations with native tribes.

Their territories often encompass land claimed by multiple colonies.

After the war begins, the leaders of the British Army establishment tried to impose constraints and demands on the colonial administrations.

The governments of both Britain and France, following the beginning of open conflict between French and British colonists in 1754 with the Battle of Jumonville Glen, had sent regular army troops to North America to further contest the disputed territories of the Ohio Country and other border areas, including the frontier between the French province of Canada and the British province of New York, an area in present-day Upstate New York that is largely controlled by the Iroquois nations.

Part of the British plans for 1755 had included an expedition to take Fort Niagara at the western end of Lake Ontario.

The planned route for this expedition had followed the Oswego River to the lake, with a major base of operations at the mouth of the river (where the present-day city of Oswego, New York is located).

Under the direction of William Shirley, the governor of the Province of Massachusetts Bay, the original Fort Oswego had been reinforced, and two additional forts, Fort George and Fort Ontario, had been built in 1755.

The planned expedition to Fort Niagara never took place due to logistical difficulties, and the fortifications around Oswego had been manned during the winter of 1755–56.

The French in 1755 had the only large naval vessels on Lake Ontario, and moved freely about the lake, between Fort Niagara in the west and Fort Frontenac at the head of the Saint Lawrence River.

Following the failure of aggressive British campaign plans in 1755, a chain of forts along the Mohawk River riverway connecting the Hudson River to Lake Ontario have been garrisoned during the winter of 1755–1756.

The largest garrison is left at Fort Oswego, at the end of the chain, which depends on the others for its supplies.

Two forts along the Oneida Carry are a key element of this supply chain.

The Oneida Carry traverses an unnavigable section between present Rome, New York and Wood Creek that is between one and six miles long, depending on seasonal water levels.

Fort Williams, on the Mohawk, is the larger of the two, while Fort Bull, several miles north of Fort Williams on Wood Creek, is little more than a palisade surrounding storehouses.

Fort Bull is garrisoned by a small number of men from Shirley's Regiment under William Bull, and holds large quantities of military stores, including gunpowder and ammunition, destined for use in the 1756 campaign.

French military leaders in Canada decide in early 1756 to send a raiding expedition to attack Oswego's supply line. 

A company of men had left Fort de La Présentation on March 12 to begin an overland trek toward the Oneida Carry.

Under the command of Lieutenant Gaspard-Joseph Chaussegros de Léry, a Canadian-born seigneur, the force consists of eighty-four troupes de la Marine, one hundred and eleven Canadian militiamen, and one hundred and ten natives, mostly Iroquois but also some Hurons.

Chaussegros de Lery, having joined the colonial army in 1733 and become an assistant engineer in 1739, had taken part in raids against the British in New England, helped maintain French fortifications in New France and was in charge of the construction of Fort Saint-Jean.

In 1753, he married Louise, the daughter of François Martel de Brouague, commandant of the Coast of Labrador.

Léry's war party, after nearly two weeks of difficult winter travel, arrives on March 24 near the carry.