Duke of Hereford is in Dukedoms of England Alphabetically, Dukedoms of England Chronologically, Merged with the Crown Dukedoms of England.
Summary
29th September 1397. 1st. King Henry IV of England [aged 30] created.
30th September 1399. 1st. Edmund Mortimer 5th Earl March 7th Earl of Ulster [aged 7] merged with the crown. See Abdication of Richard II.
On 29th September 1397 Henry Bolingbroke [aged 30] was created 1st Duke of Hereford.
On 30th September 1399 King Henry IV of England [aged 32] became King of England usurping the throne of his cousin Richard II [aged 32] and Richard's heir, the seven year old Edmund Mortimer 5th Earl of March [aged 7] who was descended from Edward III's second son Lionel of Antwerp Duke of Clarence. This second usurption was to have far reaching consequences since it subsequently became the descent by which the House of York claimed precedence over the House of Lancaster being one of the causes of the Wars of the Roses. Duke Lancaster, Duke of Hereford, Earl Derby, Earl Lancaster and Earl of Leicester merged with the Crown.
Ralph Neville 1st Earl of Westmoreland [aged 35] was appointed Earl Marshal.