Almost indisputably, the best uncle of the medieval period was Jasper Tudor. He was utterly devoted to his nephew, the future King Henry VII.
However, there is also a medieval uncle who was loyal to his nephew yet does not get nearly enough credit for it — John of Lancaster, 1st Duke of Bedford.
John was born the third surviving son of King Henry IV on 20 June 1389, when his dad was still only Henry of Bolingbroke and married to Mary de Bohun. By the time his elder brother, King Henry V, died on 31 August 1422, John was the eldest surviving son of Henry IV. The second brother, Thomas, Duke of Clarence, had died of his only military foolishness in France in 1421. The only thing between John and the throne of England was the six month old infant son of his brother and Queen Catherine of Valois. If anything should happen to the tiny King Henry VI, then John of Lancaster would be King John II of England.
Babies died very, VERY easily of multiple caused back then. Only 2/3 of children made it to age 5, so an infant king’s death wouldn’t have even been THAT suspicious. Moreover, Bedford was an able military commander with a slew of loyal followers. The only think holding him back from the throne was his moral reluctance to murder his own nephew.
John chose honor and decency over ambition. Although he quarreled over power with his little brother, Humphrey, Duke of Gloucester, they both kept baby Henry safe.
Bedford was declared Regent but focused on the ongoing war in France, while during his absence Gloucester acted as Lord Protector of England. Bedford defeated the French several times, most notably at the Battle of Verneuil, until the arrival of Joan of Arc rallied the opposition. In 1431, Bedford had Joan tried and executed at Rouen, then arranged a coronation for the young Henry VI at Paris … John died in 1435 during the Congress of Arras at his Castle of Joyeux Repos in Rouen and was buried at Rouen Cathedral.
After John’s death, his brother Humphrey also served King Henry VI loyally, in spite of the fact Humphrey’s own popularity among the English could have secured him the throne.
When 16 year old Henry VI began acting as king in 1437, he favored a new policy of peace in France espoused by his councilors Cardinal Beaufort and William de la Pole, Earl of Suffolk, shutting out his loyal uncle Humphrey and another high-born hawk, Richard, Duke of York. Humphrey discovered the king’s loyalty to family did not match his own. On 22 February 1447, Humphrey was arrested for treason and died three days later at Bury St Edmunds, and was interred St Albans Abbey.
With both his loyal uncles dead, Henry VI would discover that family members who chose love over ambition were hard to come by. In 1452, the 3rd Duke of York moved to take the throne, “but not to become king himself. Protesting his loyalty, he aimed to be recognised as Henry VI’s heir apparent (Henry was childless after seven years of marriage), while also trying to destroy the Earl of Somerset, who Henry may have preferred to succeed him over York, as a Beaufort descendant.”
When Henry VI’s wife, Margaret of Anjou, gave birth to a little boy, Edward of Westminster, in 1453 York’s apple cart was well and truly upset. Eventually, York’s eldest son would murder Edward of Westminster and be crowned Edward IV.
In time, Edward IV’s own sons were murdered after their uncle, Richard III, became king in their place.