John Mowbray, 2nd Duke of Norfolk

This and the fact that his mother lived to old age and held a third of his estates in dower, meant that until the last few years of his life he was, although an important political figure, poorly-off financially.

Probably due to the need to augment his income, he took the still-popular path for young members of the English nobility by taking part in the Hundred Years' War in France.

[5] Chris Given-Wilson has noted that in spite of this spirit of reconciliation, none of the heirs received outright their treacherous fathers' lands, and that this, therefore, made John Mowbray more likely to be "dependent on the crown" for additional sources of income.

[7] By April the next year, Mowbray indentured with the King for military service in France, contracting to supply four knights, forty-five men at arms, and 150 archers.

[8] So poor were Mowbray's finances at this time that he had had to borrow 1,000 marks from the Earl of Arundel; worse, he had to resort to the "dubious practice" of claiming that innocent—but prosperous—townsmen (from Norwich, for example) were in fact runaway villeins, and effectively blackmailed them with manumission fines.

[6] The King's expedition was due to leave from Southampton in August 1415; just before it did, however, a treasonous plot against Henry V was uncovered, which involved his cousin, Richard, Earl of Cambridge.

In his capacity as Earl Marshal, Mowbray led the investigation into the plot on 1 August; four days later he sat in judgement upon them in a trial which ultimately condemned the conspirators to death.

As a result, John Mowbray was unable to take part in what became the most famous battle of the campaign, at Agincourt, which took place on 25 October soon after he left France.

He recuperated at his family seat at Epworth, Lincolnshire, although he had recovered sufficiently by November to travel to London to welcome the victorious Henry V home.

He passed Christmas 1419 with the king at his Rouen base, until March, when he captured the town of Fresnay-le-Vicomte (with John Holland, Earl of Huntingdon), which was followed by the Battle of Le Mans the same month, in which the Dauphin, Charles Valois, was routed.

[2] Mowbray was still in France when King Henry returned in 1421, maintaining a front line at Vermandois, Tierche and the Laonnois against La Hire and Jean Poton de Xaintrailles.

He attended parliament that year, although he was summoned under the name "Thomas", and Archer posits that that clerical error is indicative of how little, due to his French service, he was known in England.

Ralph Griffiths has also suggested that Norfolk's admission to that body "provided an injection of youth into discussions hitherto conducted by a rather elderly group.

"[13] He was not a particularly regular attendee to the council,[13] and within a year, he had contracted again to serve abroad, on this occasion bringing 115 men-at-arms and 300 archers with Lords Willoughby, Hungerford, and the Duke of Exeter.

Although Mowbray did not participate in the Battle of Cravant, which took place on 31 July 1423, he was not inactive; having taken part in so many sieges in his career, he was assisting Jean de Luxembourg in his efforts to relieve Bohain, and later the Lyonnais castle of La Folleye.

[13] John Mowbray nearly drowned in the River Thames in November 1428 after his barge capsized after hitting a pier beneath London Bridge; he lost a number of his household in this accident.

[13] In an attempt to aid the Duke of Burgundy, Norfolk launched an assault on Gournay-sur-Aronde with 1,000 men and likewise took part in other attacks on Dammartin and La Chasse in the Île-de-France.

[2] In spite of his years of fighting there, however, he had never received any lands or titles based on conquest[2] (although he did manage to sell a large number of French prisoners to Lord Fanhope).

As these lands were concentrated in East Anglia, for the first time, a Mowbray Duke of Norfolk had substantially expanded his natural patrimony out of and away from Lincolnshire.

[2] Seventeen-year-old John Mowbray succeeded his father to the dukedom of Norfolk in October 1432, while Katherine lived for over fifty years more and married three more times.

Elizabeth married Michael de la Pole, 3rd Earl of Suffolk, although, as K. B. McFarlane noted, his family was, although later ducal, both "impoverished and discredited and also parvenu", they had no sons.

[20] Isabel married twice: firstly to Sir Henry Ferrers of Groby ("heir of an ancient but minor lordly house") and latterly, to James Berkeley ("one of two claimants to the headship and depleted lands of another").

Most councils he attended were mostly focused on organising his foreign expeditions; in fact, he "did the minimum amount expected" of him in terms of the running of the country during the king's minority.

[2] She does, however, note that being on friendly relations with both the Duke of Gloucester and Cardinal Beaufort as he was throughout the king's minority, he was active in keeping the peace and arbitrating between them on occasions during their periodic feud.