Richard III is the last of the four plays in Shakespeare's minor tetralogy of English history: it concludes a dramatic chronicle started by Henry VI: Part I and then moving through Henry VI: Part II and Henry VI: Part III. The entire four-play saga was composed early in Shakespeare's career, most scholars assigning Richard III a composition date of 1591 or 1592. Culminating with the defeat of the evil King Richard III at the battle of Bosworth field in the play's final act, Richard III is a dramatization of actual historical events that concluded in the year 1485, when the rule of the Plantagenet family over England was replaced by the Tudor monarchy. A full century after these events, Shakespeare's Elizabethan audiences were certainly familiar with them (as contemporary Americans are of their own Civil War), and they were particularly fascinated with the character of Richard III. Shakespeare's audiences could readily identify the various political factions and complex family relationships depicted in the play as they proceed from the three parts of Henry VI.
Today, readers and audiences may find it exceedingly difficult to follow the overlapping webs of political intrigue, family relationships, and personal vendettas. Fortunately, while a full knowledge of historical context would certainly enhance a modern reading of the text, it is not really necessary. The play, in fact, is dominated by Richard the hunchback Duke of Gloucester, who becomes Richard III through a series of horrible acts, killing off his enemies, his kinsmen, his wife and most of his supporters before reaching the Battle of Bosworth and crying out "My kingdom for a horse." In a work that is as much melodrama as history, Richard is a pure, self-professed villain of monstrous proportions. His evil drives the plot; and until his final defeat by the Duke of Richmond (who became Henry VII) in the play's last act, the good forces opposing him are weak, splintered, and ready prey for his schemes.