Adam Orleton, bishop of Hereford (died 1345)
Appointed bishop of Hereford by Pope John XXII in 1317 and later moved to the see of Worcester (1327) and then Winchester (1333). Adam may have come from the Herefordshire village of Orleton, a Mortimer manor, and in 1322 Edward II accused him of aiding Roger Mortimer and his uncle Roger Mortimer of Chirk during the Contrariant rebellion by sending them armed men. It's impossible to say whether that's true or not; Adam most probably sympathised with the Mortimers and showed loyalty to the family, but that doesn't necessarily mean that he aided them in a rebellion against the king. Edward, however, was determined to think the worst of the bishop. When the king arrived in Hereford during his campaign against the Marchers, the Contrariants as he called them, in late January 1322, he publicly upbraided Adam for supporting the rebels and went hunting in his parks with his half-brother the earl of Kent, without Adam's permission.
It was Roger Mortimer's escape from the Tower in August 1323, however, that really prompted full-out attack by Edward II on Adam Orleton. Unable to recapture Roger, in 1324 Edward lashed out at some of Roger's family and adherents, and the unfortunate Adam was the main victim of the king's vengeance. Edward accused him of treason, and at a special assize the bishop was found guilty of having sent armed men to the Mortimers some years earlier (which I certainly wouldn't assume means he actually was guilty). Edward had Adam's lands and goods seized, and even allowed his goods to be thrown into the street and ransacked by passersby. Despite the best efforts of Pope John XXII and his envoys who visited England, nothing and no-one could mitigate Edward's rage against Adam, and he lived in some poverty for the rest of the king's reign. It is entirely unsurprising to find that he supported Roger Mortimer and Isabella in 1326/27.
John Droxford, bishop of Bath and Wells (died 1329)
Appointed bishop of Bath and Wells by Clement V in 1309, at Edward II's request. John Droxford was for many years a loyal servant of Edward II and high in his favour, and was one of the bishops who supported the king at the time of Piers Gaveston's return from his second exile in 1309. In 1321/22, however, he sympathised with the Contrariants, or at least the king believed that he did, and Edward sent a series of furious and highly emotional letters to John XXII about him, Adam Orleton (above) and Henry Burghersh (below), calling them 'the worst poison' and saying that they were 'descended from the race of traitors' and had brought manifold disasters to his kingdom. He demanded that John XXII translate the three men to sees outside England, as he could no longer bear the scandal of having them in his kingdom, and asked him to replace John Droxford as bishop with his (Edward's) close personal friend William, abbot of Langdon in Kent. The pope refused, and clearly was deeply annoyed with Edward.
Henry Burghersh, bishop of Lincoln (died 1340)
Appointed bishop of Lincoln by John XXII in 1320, with Edward II's approval, though he was still under thirty. Henry was the nephew of Bartholomew, Lord Badlesmere, steward of Edward II's household who later joined the Contrariant rebellion and - poor man - suffered the traitor's death in April 1322. Henry's brother Bartholomew Burghersh was imprisoned in the Tower of London after the rebellion, and remained there until the end of Edward II's reign. The king's wrath also fell on Henry, and as early as 8 December 1321, he wrote to John XXII to tell him that he had been deceived as to Henry's ability and suitability for his post, and was now totally convinced that Henry was unsuited to be bishop. Of course you were, Edward, of course, and that had nothing at all to do with your loathing of his uncle, did it? Henry was one of the three men about whom Edward sent a series of highly emotional and overwrought letters to the pope, above.
John Stratford, bishop of Winchester (later archbishop of Canterbury; died 1348)
Apppointed bishop of Winchester by John XXII in April 1323, to the great annoyance of Edward II, who had wanted the see for his and Hugh Despenser the Younger's clerk Robert Baldock. The king asked the pope to revoke the appointment, and also asked three men – Archambaud IV, count of Périgord, Bernard Jordani, lord of L'Isle Jourdain, and Peter de Via, the pope's relative – to use their influence with John in the matter, but to no avail: John XXII informed him that he had already consecrated John Stratford when he received Edward's letters recommending Robert Baldock.
Edward pettishly refused to grant the petition of one Raymond de Busselers in the summer of 1323 because it was supported by Stratford, with whom he declared himself "exceedingly incensed" and described as "faithless and ungrateful."  In November 1323, Edward ordered the keepers of more than seventy ports and the sheriffs of twenty counties not to permit John to leave the country, claiming that John had refused to meet the king's counsellors and "withdrew himself by subterfuge" from him.  He forced John to acknowledge a huge debt of £10,000 to him in June 1324, and began proceedings against him before the King's Bench.  John XXII wrote to Hugh Despenser, whom he frequently addressed as "one able to influence the king," thanking him for his efforts in attempting to reconcile Stratford and Edward and asking him to continue his exertions. Hugh responded in typical fashion by extorting £1000 from the unfortunate bishop, which he deposited with his Italian bankers, the Peruzzi. Superficially the king and bishop were reconciled in June 1324, and Stratford worked on Edward's behalf in France in 1325, but in 1326/27 supported Isabella and Roger Mortimer, and was one of the authors of the articles of deposition.
[1) Foedera, p. 527.
2) Chancery Warrants 1244-1326, p. 546; Close Rolls 1323-27, pp. 147-8.
3) Foedera, p. 541; Close Rolls, p. 198.]
John Hothum (or Hotham), bishop of Ely (died 1337)
Appointed to the bishopric of Ely in 1316, and for many years high in Edward II's favour; John acted as Piers Gaveston's attorney in 1311, and Edward made him treasurer then chancellor of England in 1318 and 1320. For some obscure reason John seems to have angered Edward, and he acknowledged a massive debt of £2000 to Hugh Despenser the Younger in November 1324 (Close Rolls 1323-27, p. 325). I don't know what that was about, but John joined forces with Isabella after the invasion.
William Airmyn (or Ayreminne), bishop of Norwich (died 1336)
Another bishop on whom Edward II's wrath fell after William was made bishop of Norwich in July 1325, John XXII once again passing over Edward's choice, Robert Baldock. Edward had previously favoured William, and had asked John XXII some months earlier to provide Airmyn to the bishopric of Carlisle, unsuccessfully; John Ross gained the position. Edward, in his usual fashion when someone annoyed him, decided unfairly to blame and to scapegoat William for the unfavourable peace treaty of summer 1325 with his (Edward's) brother-in-law Charles IV of France, and summoned William twice to appear before King's Bench on a charge of maliciously and treacherously agreeing that the king of France should continue to hold some of Edward's inheritance (the Agenais). He even ordered the arrest of William's two brothers when he failed to appear. Thus persecuted by the vengeful vindictive king, William Airmyn fled to France and joined Isabella sometime between March and June 1326. It has often been wrongly assumed that William was chosen as bishop of Norwich because Isabella had intervened with the pope on his behalf, but in fact it is clear from John XXII's letters to Edward II that he thought he would be pleasing the king with the appointment (given that Edward had only recently asked the pope to provide William to a bishopric), and that Isabella's letters had reached him too late to have any effect on his decision.
And so Edward II alienated yet another man who would have been a very useful ally to him. I should point out here that the king did stay on good terms with other English bishops in the 1320s, especially William Melton, archbishop of York, Hamo Hethe of Rochester, John Ross of Carlisle, Thomas Cobham of Worcester and Stephen Gravesend of London. Walter Stapeldon, bishop of Exeter and former treasurer of England (and founder of Exeter College at Oxford University in 1314) died for his loyalty to Edward, suffering the horrible fate of being beheaded with a bread knife in London after Isabella and Roger Mortimer's invasion in 1326, his head sent to Isabella. Archbishop Melton and Bishop Gravesend were involved in the plot of Edward's half-brother the earl of Kent to free him in 1330. Neither was Edward II the only king to have problems with his bishops: Robert Winchelsey, archbishop of Canterbury, was a fierce opponent of Edward I and was forced into exile from England in 1305, and Edward III and Archbishop John Stratford went through their own crisis in 1340/41. And yet, Edward II's alienating so many influential men played an important role in the revolution of 1326/27 and in his forced abdication; Adam Orleton and John Stratford were among the prime movers of these events. Even Edward's long-term friend Walter Reynolds, archbishop of Canterbury, hesitated to support him after the invasion in 1326 and then enthusiastically joined Isabella's side. Edward's losing his temper with him at some point in the 1320s and screaming in his face, so that Walter pretended he had to make an urgent visitation to his cathedral in order to escape from the king's presence, can't have helped.
Most of Edward II's behaviour in the 1320s really leaves me shaking my head...
- Roy Martin Haines, The Church and Politics in Fourteenth-Century England: the Career of Adam Orleton, c. 1275-1345 (1978)
- Roy Martin Haines, Archbishop John Stratford: Political Revolutionary and Champion of the Liberties of the English Church, ca. 1275/80-1348 (1986)
- Kathleen Edwards, 'The Personal and Political Activities of the English Episcopate During the Reign of Edward II', Bulletin of the Institute of Historical Research, 16 (1938)
- Kathleen Edwards, 'The Political Importance of the English Bishops During the Reign of Edward II', English Historical Review, 59 (1944)
- J.L. Grassi, 'William Airmyn and the Bishopric of Norwich', English Historical Review, 70 (1955)
- Seymour Phillips, Edward II (2010)
- Roy Martin Haines, King Edward II: His Life, His Reign, and Its Aftermath, 1284-1330 (2003)