The Chevalier de Levis was appointed second in command.
No sooner did Montcalm arrive in America, than difficulties arose between him and the Marquis de Vaudreuil, the governor, who had hoped to have himself received the appointment of commander of the French forces, and who, in virtue of his office, commanded the Canadian militia.
From first to last this man opposed and thwarted Montcalm, doing all in his power to injure him, by reports to France in his disfavour.

The misfortunes which befell France during the war were, in no slight degree, due to this divided authority, and to the obstacles thrown in the way of Montcalm by the governor.
Montcalm's first blow against the English was struck in August, 1756, six months before the attack on Fort William Henry, which had been arranged by Vaudreuil.

Three battalions of regular troops, with 700 Canadians and 250 Indians, with a strong force of artillery, were quietly concentrated at Fort Frontenac, and were intended for an attack upon the important English post of Oswego.

Fighting had been going on in this neighbourhood for some time, and it was from Oswego that Shirley had intended to act against Niagara and Frontenac.

That enterprise had fallen through, owing to Shirley having been deprived of the command; but a sharp fight had taken place between Colonel Bradstreet and his armed boatmen, and 1100 French, who were beaten off.
Oswego was a place of extreme importance.