A civil war in England between the House of Lancaster and House of York. The badges of the two houses were a red rose for Lancaster and a white rose for York, hence the name. "Forge ahead York! Forge ahead Lancaster!"
Opinions may vary as to when the Wars of the Roses began and ended, but the armed conflict was concentrated in the period 1455-1485. The origins of the antagonism between the two houses, however, originated with the overthrow of King Richard II of England by his cousin, Henry Bolingbroke, Duke of Lancaster, in 1399. Henry IV of England had a poor claim on the throne, and was tolerated as king only because Richard had been unpopular. Henry's heir, Henry V of England, was a great soldier and gained a firm hold on the reins of power, but was not without enemies. One of these was Richard, Earl of Cambridge, a son of Edmund of Langley and thus grandson of King Edward III of England. Cambridge was executed for treason at the start of the campaign leading up to the Battle of Agincourt.
Cambridge's wife, Anne Mortimer, also had a claim to the throne, being descended from Lionel, Duke of Clarence, an older son of Edward III. Their son, Richard, Duke of York, grew up to challenge the feeble King Henry VI of England for the crown. When York was killed at the Battle of Wakefield in 1460, his claim was taken forward by his eldest son, an outstanding warrior who prevailed over the Lancastrians at the Battle of Towton in 1461 to become King Edward IV of England. Edward's mentor, Richard Neville, Earl of Warwick - "the Kingmaker" - later changed sides after being slighted by the young king, and transferred his allegiance to Henry VI's queen, Margaret of Anjou, triumphing over Edward and restoring Henry briefly to the throne in 1470.
Warwick's success was short-lived. With assistance from Burgundy, Edward returned and Warwick was defeated and killed at the Battle of Barnet in 1471. The remaining Lancastrian forces were destroyed at the Battle of Tewkesbury and the Lancastrian heir to the throne was killed. Henry VI was murdered shortly afterwards, to strengthen the Yorkist hold on the throne.
Peace was restored for the remainder of Edward's reign, but he died suddenly, in 1483, leaving the kingdom in the hands of his twelve-year-old son, Edward V of England. The throne was quickly usurped by Edward IV's surviving brother, Richard III of England, and the resulting division of loyalties strengthened the Lancastrian cause, which was now focused on Henry Tudor, whose father, Edmund Tudor, Earl of Richmond, had been a half-brother of Henry VI. However, it was through his mother, Margaret Beaufort, a descendant of Edward III, that Henry's claim on the throne rested. By a combination of luck and good judgement, Henry defeated Richard at the Battle of Bosworth Field in 1485 and became King Henry VII of England. Henry strengthened his position by marrying Elizabeth of York, daughter of Edward IV, who was the best surviving Yorkist claimant.
Some would argue that the Wars of the Roses concluded only with the Battle of Stoke in 1487, which arose from the appearance of a pretender to the throne, a boy named Lambert Simnel who had been selected for his close physical resemblance to the young Earl of Warwick, York's best surviving male claimant. It was at this battle that Henry defeated forces led by John de la Pole, Earl of Lincoln - who had been named by Richard III as his heir, but had been reconciled with Henry after Bosworth - thus effectively removing the remaining Yorkist opposition. Simnel was pardoned for his part in the rebellion, and sent to work in the royal kitchens.