The Despenser War (1321–22) was a baronial revolt against Edward II of England led by the Marcher Lords Roger Mortimer and Humphrey de Bohun.

The council of Ordainers was formed in 1311 to reform the King's household, restrict his royal prerogatives, supervise the economy, and they insisted on the banishment of his then-favourite, Piers Gaveston, husband of the earl of Gloucester's sister Margaret.

The passage of Glamorgan to Despenser in its entirety angered his brothers-in-law, Roger d'Amory and Hugh de Audley, who were cheated out of their share of lands which rightfully belonged to them.

[6] This provided him with a face-saving excuse to exile the Despensers and defuse the crisis, but it was clear Edward intended to arrange their return at the first opportunity.

[7] Decisive Royal victory Contrariants Supported by: Despite the momentary respite, by the autumn of 1321 tension between Edward and the baronial opposition led by Thomas of Lancaster was extremely high, with both sides raising forces across the country.

[8] At this point, Isabella undertook a pilgrimage to Canterbury, leaving the traditional route to stop at Leeds Castle; its governor, Bartholomew de Badlesmere, was steward of the King's household but by 1321 had joined the opposition.

[9] Badlesmere was away at the time, leaving his wife Margaret in charge; when she refused the Queen admittance, fighting broke out between Isabella's guards and the garrison.

It was clear his opponents could expect little mercy; when Mortimer and Hereford travelled north meet with Lancaster, the three reaffirmed their opposition to Edward.

[20] With Thomas of Lancaster's death, the Scots, who supported his rebellion as a means to cripple the English in the First Scottish War of Independence saw the opportunity to gain his possessions in The Great Raid of 1322.

Roger Mortimer was imprisoned in the Tower of London after his surrender at Shrewsbury and some of his supporters, including William Trussell, continued to raid Despenser lands.

This invasion led to the executions of the two Despensers, the deposition and killing of Edward II, and the seizure of authority by Queen Isabella and Roger Mortimer, who became the de facto rulers of England from 1327 to 1330.