Love in Idleness by F. Marion Crawford

There is nothing equal to the absolute fearlessness of a naturally brave man who has no experience of the risk he runs and is bent on saving the life of the woman he loves. Louis Lawrence remembered afterwards what he had done and how he had done it, but he was unconscious of what he was doing at the time.

He rushed down the hill between the closer trees, and with utter recklessness sprang at the bridle as the infuriated mare dashed past him. Grasping snaffle and curb -- tight drawn as they were -- in both hands, he threw all his light weight upon them and allowed himself to be dragged along the ground between the trees at the imminent risk of his life -- a risk so terrible that Fanny Trehearne turned paler for him than for her own danger. In half a dozen more strides they might both have been killed. But the mare stopped, quivering, tried to rear, but could not lift Lawrence far from the ground nor shake off his desperate hold, plunged once and again, and then stood quite still, trembling violently. Lawrence scrambled to his feet, still holding the bridle, and promptly placed himself in front of the mare.