Henry VI (6 December 1421 21 May 1471) was King of England and Lord of Ireland from 1422 to 1461 and again from 1470 to 1471, and disputed King of France from 1422 to 1453. The only child of Henry V, he succeeded to the English throne at the age of nine months upon his father's death, and succeeded to the French throne on the death of his maternal grandfather, Charles VI, shortly afterwards.

Henry inherited the long-running Hundred Years' War (13371453), in which his uncle Charles VII contested his claim to the French throne. He is the only English monarch to have been also crowned King of France, in 1431. His early reign, when several people were ruling for him, saw the pinnacle of English power in France, but subsequent military, diplomatic, and economic problems had seriously endangered the English cause by the time Henry was declared fit to rule in 1437. He found his realm in a difficult position, faced with setbacks in France and divisions among the nobility at home. Unlike his father, Henry is described as timid, shy, passive, well intentioned and averse to warfare and violence; he was also at times mentally unstable. His ineffective reign saw the gradual loss of the English lands in France. Partially in the hope of achieving peace, in 1445 Henry married Charles VII's niece, the ambitious and strong-willed Margaret of Anjou. The peace policy failed, leading to the murder of one of Henry's key advisers, William de la Pole, 1st Duke of Suffolk, and the war recommenced, with France taking the upper hand; by 1453, Calais was Henry's only remaining territory on the continent.

As the situation in France worsened, there was a related increase in political instability in England. With Henry effectively unfit to rule, power was exercised by quarrelsome nobles, while factions and favourites encouraged the rise of disorder in the country. Regional magnates and soldiers returning from France formed and maintained increasing numbers of private armed retainers, with whom they fought one another, terrorised their neighbours, paralysed the courts, and dominated the government. Queen Margaret did not remain unpartisan and took advantage of the situation to make herself an effective power behind the throne.

Amidst military disasters in France and a collapse of law and order in England, the Queen and her clique came under accusations, especially from Henry VI's increasingly popular cousin Richard, Duke of York, of misconduct of the war in France and misrule of the country. Starting in 1453, Henry had a series of mental breakdowns, and tensions mounted between Margaret and Richard of York over control of the incapacitated King's government and over the question of succession to the English throne. Civil war broke out in 1455, leading to a long period of dynastic conflict now known as the Wars of the Roses. Henry was deposed on 4 March 1461 by Richard's son, who took the throne as Edward IV. Despite Margaret continuing to lead a resistance to Edward, Henry was captured by Edward's forces in 1465 and imprisoned in the Tower of London. Henry was restored to the throne in 1470 but Edward retook power in 1471, killing Henry's only son and heir, Edward of Westminster, in battle and imprisoning Henry once again.

Having "lost his wits, his two kingdoms and his only son", Henry died in the Tower during the night of 21 May, possibly killed on the orders of King Edward. Miracles were attributed to Henry after his death and he was informally regarded as a saint and martyr until the 16th century. He left a legacy of educational institutions, having founded Eton College, King's College, Cambridge, and (together with Henry Chichele) All Souls College, Oxford. Shakespeare wrote a trilogy of plays about his life, depicting him as weak-willed and easily influenced by his wife, Margaret.

The Wars of the Roses, known at the time and for more than a century after as the Civil Wars, were a series of civil wars fought over control of the English throne in the mid-to-late fifteenth century, fought between supporters of two rival cadet branches of the royal House of Plantagenet: Lancaster and York. The wars extinguished the male lines of the two dynasties, leading to the Tudor family inheriting the Lancastrian claim. Following the war, the Houses of Tudor and York were united, creating a new royal dynasty, thereby resolving the rival claims.

The conflict had its roots in the wake of the Hundred Years' War and its emergent socio-economic troubles, which weakened the prestige of the English monarchy, unfolding structural problems of bastard feudalism and the powerful duchies created by Edward III, and the mental infirmity and weak rule of Henry VI, which revived interest in the Yorkist claim to the throne by Richard of York. Historians disagree over which of these factors were the main catalyst for the wars.The wars began in 1455 when Richard of York captured King Henry VI in battle and was appointed Lord Protector by Parliament, leading to an uneasy peace. Fighting resumed four years later. Yorkists, led by Warwick the Kingmaker, recaptured Henry, but Richard was killed in 1460, leading to the claim by his son, Edward. The Yorkists lost custody of Henry the following year but destroyed the Lancastrian army, and Edward was crowned three months later in June 1461. Resistance to Edward's rule continued but was defeated in 1464, leading to a period of relative peace.

In 1469, Warwick withdrew his support for Edward due to opposition against the king's foreign policy and choice of bride, and changed to the Lancastrian claim, leading to a renewal in fighting. Edward was briefly deposed and fled to Flanders the following year, and Henry was reinstalled as king. Henry's renewal in reign was short-lived however, as the Lancastrians suffered decisive defeats in battle in which Warwick and Henry's heir were killed, Henry was reimprisoned, and much of the Lancastrian nobility were either killed, executed, or exiled. Shortly afterwards, Edward reassumed the throne, after which Henry either died or was assassinated on Edward's order. Edward ruled unopposed and England enjoyed a period of relative peace until his death twelve years later in 1483.

Edward's twelve-year-old son reigned for 78 days as Edward V until he was deposed by his uncle, Richard III. Richard assumed the throne under a cloud of controversy, particularly the disappearance of Edward IV's two sons, sparking a short-lived but major revolt and triggering a wave of desertions of prominent Yorkists to the Lancastrian cause. In the midst of the chaos, Henry Tudor, son of Henry VI's half-brother, returned from exile with an army of English, French, and Breton troops. Henry defeated and killed Richard at Bosworth Field in 1485, assumed the throne as Henry VII, and married Elizabeth of York, the eldest daughter and sole heir of Edward IV, thereby uniting the rival claims.

The Earl of Lincoln then put forward Lambert Simnel as an impostor Edward Plantagenet, a potential claimant to the throne. Lincoln's army was defeated and Lincoln himself killed at Stoke Field in 1487, ending the wars. Henry never faced any further serious internal military threats to his reign. In 1490, Perkin Warbeck claimed to be Richard of Shrewsbury, Edward IV's second son and rival claimant to the throne, but was executed before any rebellion could be launched.The House of Tudor ruled England until 1603. The reign of the Tudor dynasty saw the strengthening of the prestige and power of the English monarchy, particularly under Henry VIII and Elizabeth I, and the end of the medieval period in England which subsequently saw the dawn of the English Renaissance. Historian John Guy argued that "England was economically healthier, more expansive, and more optimistic under the Tudors" than at any time since the Roman occupation.