As Julian had said, there were many French prisoners there, brought in from time to time after skirmishes.
They were treated exactly the same as the English wounded, and Wolfe made a point of visiting them daily, talking to them in their own tongue, and promising them a speedy exchange when any negotiation should be opened with the town.

Julian, too, went much amongst them, able to win their confidence very easily, since he seemed to them almost like a brother.

It was quite an easy thing for him to disguise himself in the white uniform of a French soldier, and to creep, under cover of the darkness, closer and closer to the wall of the town.
It so chanced that he could not have chosen a better night for his enterprise.

The booming of guns across the harbour and from the batteries behind had now become constant, and attracted little notice from sentries or soldiers beyond range.

But just as darkness began to fall, a shell from Wolfe's newly-planted battery fell upon one of the French ships in the harbour, and set her on fire.