Nell Gwynne comes of a fighting stock, and showed an early aptitude for the fray.

Trust to her, Tom, if ever you are hard pressed; she will bring you safely through, if it can be achieved at any price." And, indeed, as the travellers pursued their long ride through a disturbed and often half-hostile country, they had frequently to depend as much upon the fleetness, fidelity, and strength of their horses as upon the strength of their own right arms.
Well did Tom now understand why Lord Claud had made such a point of having their own horses with them.

Had they been jogging along upon some beast hired or purchased in the country, they would never have got through the divers perils of the way.
Once Tom was aroused from slumber in a little, ill-smelling inn by the sound of kicking and stamping proceeding from the stable; and when he had aroused his companion, and they had hastily dressed themselves and descended, it was to find that a desperate fight was going on between the two horses and a handful of French soldiers, who had followed after the fine animals, and were seeking to steal them whilst the travellers slept.
They had paid dearly for their temerity, however, for Nell Gwynne was stamping the life out of one wretched fellow; whilst Lucifer had broken the leg of a second, and had pinned his companion by the arm, so that he was yelling aloud in his agony.
Lord Claud sprang in, and at the sound of his voice the horse loosened his grip, and the man reeled hack against the wall, white and bleeding, and cursing beneath his breath.

Tom was too late to save the life of the victim of the mare's anger, but he was in time to strike up the pistol which another of the soldiers had pointed at her, in the trembling hope of saving his comrade.
"If you fire you will drive her to madness, and she will kill every man of you," said Lord Claud coolly.

"She has a devil in her, and is bullet proof; you had better leave meddling with both the beasts." The men crossed themselves in pious horror, and were glad enough to back out of the place, carrying their dead and maimed companions with them.