Remarks:
llegitimate eldest son of John of Gaunt, Duke of Lancaster, and Catherine Swynford, John was legitimised in 1397 after their marriage. He was the first to bear the name of Beaufort, which John of Gaunt chose for his children by Catherine Swynford. Also in 1397 he became Earl of Somerset, Marquess of Somerset as well as Marquess of Dorset.
In 1399 when his half-brother Henry Bolingbroke became King Henry IV John was deprived of his marquisates as well as his right to inherit the crown of England, but under King Henry IV he became chamberlain of England and captain of Calais.