Bohun spent most of his early career reconquering marcher lands captured by Llywelyn ap Gruffudd during the Welsh war in England.

At the same time he also had private feuds with other marcher lords, and his conflict with Gilbert de Clare, Earl of Gloucester, eventually ended with the personal intervention of King Edward himself.

Hereford's final years were marked by the opposition he and Roger Bigod, Earl of Norfolk, mounted against the military and fiscal policy of Edward I.

The king signed the Confirmatio Cartarum—a confirmation of Magna Carta—and Bohun and Bigod agreed to serve on the Falkirk Campaign.

Humphrey (VI) de Bohun was part of a line of Anglo-Norman aristocrats going back to the Norman Conquest, most of whom carried the same name.

[1] Part of this inheritance, the marcher lordship of Brecon, was in the meanwhile given to the custody of Gilbert de Clare, Earl of Hertford.

Humphrey technically regained his lordship from Clare in 1270, but by this time these lands had effectively been taken over by the Welsh prince Llywelyn ap Gruffudd, who had taken advantage of the previous decade's political chaos in England to extend his territory into the Marches.

[12] On 12 November 1276, Hereford was present at a royal assembly where judgment was passed on Llewelyn,[7] and in 1277, Edward I declared war on the Welsh prince.

[15] After the campaign was over, on 2 January 1278, he received protection from King Edward to go on pilgrimage to Santiago de Compostela in Spain.

To men like Hereford, this was preferable, because as part of a feudal army the participants would have both a stake in the war and a justifiable claim on conquered land.

[17] Hereford jealously guarded his authority as hereditary Constable of England, and protested vigorously when the Gilbert de Clare, Earl of Gloucester was appointed commander of the forces in South Wales.

[32] The main reason for the magnates' defiance was the heavy burden of taxation caused by Edward's continuous warfare in Wales, France and Scotland.

[33] At one point Bohun and Bigod turned up in person at the Exchequer to protest a tax they claimed did not have the consent of the community of the realm.

[34] For Hereford there was also a personal element in the opposition to the king, after the humiliation and the affront to his liberties he had suffered over the dispute in the Marches.

[35][36] At a meeting just outside London, Bohun gave an impassioned speech objecting to the king's abuse of power and demanding the restoration of ancient liberties.

[41] The earls consequently consented to serve with the king in Scotland, and Hereford was in the army that won a decisive victory over the Scots in the Battle of Falkirk in 1298.

[7] Hereford, not satisfied that the king had upheld the charter, withdrew after the battle, forcing Edward to abandon the campaign.

[1] His career was marked by turbulence and political strife, particularly in the Marches of Wales, but eventually he left a legacy of consolidated possessions there.

In 1297, at the height of the conflict between Edward I and rebellious barons, the king had actively tried to undermine Hereford's authority in the Marches, but failed due to the good relations the earl enjoyed with the local men.