These French victories could not, however, offset their serious weaknesses. Forbes, becoming increasingly ill - he was now being carried on a stretcher - understood this well. His troops were certainly unable to carry out raids, but with their numbers and the strength of their artillery they would be able to take Fort Duquesne. As the Amerindians, who could sense a change in the wind, began to abandon him in growing numbers, Lignery was equally aware of this. On November 26, when Forbes' army was only a few kilometres away, he sent his garrison to the small forts of Machault and Massiac and blew up Fort Duquesne. The Anglo-Americans built another fort on that very site, called Fort Pitt or Pittsburgh, which was to become a major city in Pennsylvania.
The taking of Fort Frontenac (present-day Kingston, Ontario) by Lieutenant-Colonel John Bradstreet amounted to another French defeat. His 3,000 men, nearly all militiamen from the American colonies, crossed Lake Ontario in boats and assaulted the fort. The 110 men in the garrison held for three days before surrendering on August 28. Bradstreet withdrew after burning and demolishing the fort. In the short term, the strategic consequences of the destruction of Fort Frontenac were not serious, but for the first time French communications with Niagara, Detroit and the Ohio forts were seriously threatened.
The year 1758 thus ended with significant gains by the British: in spite of the Carillon French victory, they had taken part of the Ohio Valley and, most importantly, the fortress of Louisbourg, thus opening the way to Quebec. Vaudreuil and Montcalm were keenly aware of this, and in spite of their differences agreed to beg the French authorities to send a large number of reinforcements, the fate of New France more than ever in the balance. To plead the cause of the colonies, they sent Louis-Antoine de Bougainville to Versailles. This young and brilliant staff officer of Montcalm's, destined to become one of the great explorers of the Pacific, did everything in his power. But prospects for the French armies and fleets in Europe were dim indeed. The Minister of the Navy, Berryer, told him curtly, "When the house is on fire, you don't worry about the stables."