Heyward's party returns to Fort William Henry through French lines in a hazardous night crossing that turns on fog, uncertain direction, and a sudden recognition at the fort. The escape ends when Alice calls to her father from the mist: Colonel Munro orders his soldiers not to fire, the sally-port opens, and the sisters are reunited with him.

The crossing under cover of fog

From the mountain, Hawkeye leads the party toward the plain opposite a western sally-port, about half a mile from where he pauses for Duncan Heyward. The travelers have moved faster than the fog descending over the lake, so they wait for the mist to conceal the enemy camp. The Mohicans scout ahead, while Hawkeye follows to learn from their observations and assess the nearby ground.

Their route is threatened by a French picket positioned directly across their path. Hawkeye discovers the obstacle and warns the others that the party could blunder into the soldiers even in the fog. As the mist thickens, Heyward places himself between Cora Munro and Alice Munro and hurries after Hawkeye; within a short distance, the travelers can scarcely make out one another.

Confusion between the armies

The party believes it has crossed much of the distance to the fort when a French challenge sounds close by. Their attempt to pass as friends of France fails: the picket orders its men to fire, and fifty muskets discharge into the fog. The shots miss the fugitives, but the French pursue. Hawkeye proposes returning fire, hoping to make the French mistake it for a sortie and pause for reinforcements; instead, gunfire spreads across the plain, making the party's position more precarious.

A mistaken sense of direction compounds the danger. Hawkeye realizes that the sound they took to be the fort came from the French, and that they have been moving toward the woods, where hostile pursuers are closing in. Heyward shifts Cora's support to Uncas, and the party turns back toward the fort as its pursuers draw near.

Recognition and rescue

The crisis breaks when Alice calls out to her father from the mist and begs him to spare his daughters. Colonel Munro recognizes her voice and orders the defenders to hold their fire, open the sally-port, and drive off the French with their weapons rather than risk striking the returning party. Heyward reaches the opening by following the sound of its hinges, recognizes his battalion of the Royal Americans, and leads them against the pursuers until they are cleared from before the works.

Cora and Alice stand bewildered for a moment after the sudden change from flight to safety. Colonel Munro then rushes out of the mist, embraces both daughters, and gives thanks that he has been restored to them. The reunion resolves the crossing's immediate peril and brings the sisters back within the fort.

Place in the siege narrative

The return is a narrow escape rather than a military victory: the fog that conceals the party also blurs its route and makes recognition between friend and enemy uncertain. Its decisive turn comes not from a clear view of the fort, but from Alice's voice, which enables Munro to distinguish his daughters from the enemy and restrain his own defenders.

The reunion precedes the fort's surrender. Later, Montcalm tells Munro that the fort must be destroyed for the interests of his sovereign, while promising military privileges to the garrison. Munro signs terms allowing the defenders to retain their arms, colors, and baggage as they leave the following morning. The return thus restores the family briefly within the besieged fort, but does not prevent its eventual capitulation.