York had already succeeded in obtaining a promise from King Henry VI of England that, on Henry's death, the crown would pass to him and his heirs. Queen Margaret was unwilling to accept this promise, which had been obtained by force, and was determined to protect the inheritance of her only son, Edward, Prince of Wales, then aged about six. With a force outnumbering that of the Yorkists, she marched north to confront the Duke. The details of what ensued are not entirely clear, and most people are more familiar with William Shakespeare's melodramatic version of events, notably the "murder" of York's second son, Edmund, Earl of Rutland.
In Shakespeare's play, Edmund is depicted as a small child, and, following his unnecessary slaughter, Margaret torments his father, York, before murdering him also. In fact, the Duke of York was killed during the battle, and his son, Edmund, at seventeen, was more than old enough to be an active participant in the fighting. York's defeat was probably the result of his own over-confidence, as he apparently refused to wait for reinforcements to arrive before leaving his stronghold at Sandal Castle to meet the Lancastrians.
The outcome was important mainly because it left York's eldest son, Edward, as the Yorkist pretender to the throne. Edward, though young, would prove an outstanding battle commander and a consummate politician, and would eventually reign as King Edward IV of England.