Walter Scott 
Black Dwarf 

The Black Dwarf is set in the immediate aftermath of the Union between England and Scotland in 1707. The political action is centred on the first uprising to be attempted by Jacobites after the Union, the aborted landing of the exiled James Francis Edward Stuart and a large French fleet in March 1708. The dwarf of the title is Sir Edward Mauley, who, in his youth, has embraced the quarrel of his friend and kinsman Richard Vere, killing his rival the Laird of Earnscliff. While imprisoned for manslaughter, he learns that Vere has betrayed him by marrying his intended bride. How does the dwarf plan to take vengeance? (Goodreads)