Shakespeare's original audience had an advantage over modern readers since they would have been familar with the then relatively recent history portrayed and dramatized in his "histories"—including the eight plays that choncile (more or less) the upheavals of a roughly 85-year period in English history that historians have labeled "The Wars of the Roses."
Starting near the beginning of the fifteenth century, England’s royal family was locked in a power struggle that periodically erupted into violence. The name "Wars of the Roses,"references the symbols of the two related but competing families: the Lancasters, symbolized by a red rose, and the Yorks, symbolized by a white rose. Shakespeare’s eight main history plays about this period—Richard II, Henry IV, Part 1; Henry IV, Part 2; Henry V; as well as Henry VI, Part 1; Henry VI, Part 2; Henry VI, Part 3; and Richard III—cover these events. Shakespeare often plays fast and loose with the facts, stretching and altering the timeline to suit his dramatic purposes, but the plays generally are based upon historical records.
The problems began in the late fourteenth century with the death of the long-reigning King Edward III, of the house of Plantagenet. Edward III had seven sons, of whom the fourth and fifth became the fathers of dynasties. The elder was called John of Gaunt, the duke of Lancaster, and his younger brother was called Edmund of Langley, duke of York. Their descendants formed two important clans—the Lancasters and the Yorks. Both clans derived from royal blood, and both produced ambitious men who were willing to fight for the throne. The Lancasters and their allies are sometimes called the Lancastrians; the Yorks and their allies are called the Yorkists.
After the death of Edward III in 1377, King Richard II—who was descended from Edward’s deceased eldest son and was thus neither a York nor a Lancaster—ruled for twenty-two years. However, he was eventually overthrown by his cousin (the son of John of Gaunt), a Lancaster named Henry Bolingbroke who became Henry IV in 1399. Henry IV was in turn succeeded by his son, Henry V in 1413, who was succeeded by his son, Henry VI, in 1421.
But in the late fifteenth century, fighting broke out again, this time between Lancasters and Yorks. After a bloody struggle, the Lancastrian Henry VI was deposed in 1461, and the head of the house of York took the throne as King Edward IV. Henry VI briefly resumed the kingship in 1470, but again he was deposed. In 1471, Henry's son and destined heir, known as Edward, Prince of Wales (a title always given to the current heir to the throne), was killed in battle, and Henry was put to death. The sons of the York family—King Edward IV, Clarence, and their younger brother Richard—were victorious. After the executions, Edward took the throne once again. The action of Richard III begins shortly after this event, but the hostility between the two families was much older. The Lancastrians had killed a second York son—Edmund, earl of Rutland—when he was still quite young.