Throughout his life, Bonville was despatched on further operations in France, but increasingly events in the south-west of England took up more of his time and energy, as he became involved in a feud with his powerful neighbour Thomas Courtenay, Earl of Devon.

[15] The couple required papal dispensation to marry because Elizabeth was already a godmother to one of Bonville's daughters and in the eyes of the church this placed her within a prohibited degree of consanguinity.

[7] As such, when Bonville came of age in 1414[10] he inherited an income of approximately £900 per annum; for context, the historian Martin Cherry says this was "a figure not far short of that enjoyed by the fifteenth-century earls of Devon themselves".

These brought him the manors of Yelverton and Mudford Sock, and as a result, says the History of Parliament, "without doubt Bonville ranked among the very wealthiest landowners of the West Country".

[2] Bonville undertook royal service in France in 1415, and joined Henry V's Agincourt campaign, travelling in the retinue of the King's brother, Thomas, Duke of Clarence.

[6] In 1427 he was engaged in a bitter feud with Sir Thomas Brooke, whom Bonville—described as a "thrusting and able man"[24]—accused of unilaterally enclosing parkland in Axmouth and obstructing roads that Bonville's tenants needed to use.

[note 8] From then on he was regularly occupied with his duties as a royal official in the region: he was a justice of the peace for Devon from July 1431, for Somerset from March 1435, and for Cornwall from November 1438.

[25] Other commissions included local inquiries into necromancy, piracy, extortion, desertion (from the Earl of Warwick's fleet in 1438), felonies, smuggling and concealment of treasure.

[2] He was zealous in combating piracy off the Cornish coast, to such an extent that in 1454 the Duke of Burgundy made an official complaint to the English government about the treatment meted out to Burgundian shipping in the area.

They saw little action; the occasional encounters with the enemy did not necessarily go in their favour, as on one occasion rival Portuguese merchants captured two ships from Bonville's fleet.

[30] During the Earl's minority, Courtenay influence in Devon waned and shifted towards the county's upper gentry ("among whom Bonville was pre-eminent", argues Cherry).

[8] The historian Hannes Kleineke has argued that the minority created a power vacuum in the county which the regional gentry, such as Bonville, had helped fill.

[32] Bonville's (and other local gentry's) pre-eminence in Devon was found to be almost unassailable by the Earl, who wished to regain the regional authority that his ancestors had held.

[35][note 10] It was further exacerbated, in 1440, by what the Griffiths calls "a serious blunder" by the crown—a contemporary council minute described the grant as causing "grete trouble".

Courtenay saw his newly-reinforced position as sufficiently secure to allow him to reignite the feud with Bonville,[65] who in Taunton was recruiting men to his banner at sixpence a day.

Bonville has been described by historians connected to The Gascon Rolls Project as being "an excellent choice for lieutenant"[3][note 16] and received the constableship of Exeter Castle.

[78] He also received grants of lands and estates in South Teign, the castle, borough and manor of Lydford, the conservancy of the River Exe, and forestry rights in Dartmoor,[25] making him, wrote the historian Bertram Wolffe, "exalted in the west country".

Bonville experienced no lessening of his position during the protectorate;[88] indeed, he had committed flagrant acts of piracy against foreign shipping off the south-west coast, which went unpunished.

[2] Although clearly unwilling to turn against his King at this point,[93] Bonville did attend the Yorkist parliament of September 1455, where he voted in favour of the Duke of York's appointment as protector.

[2] He also used his local influence to ensure that the vacant Bishopric of Exeter was reserved for the Earl of Salisbury's youngest son, George Neville,[95] and in November Bonville received a general pardon.

[2] This culminated on 23 October 1455 with what has been described as the "most notorious private crime of the century",[99] when Courtenay's son—also Thomas—and a small force of men attacked and brutally murdered one of Bonville's close councillors, the prominent local lawyer Nicholas Radford.

[101] Devon had committed such offences, so Bonville said, falsely, cowardly and traitourously, in breach of his faith as a knight, his prowess and honour, his allegiance, the common good, and the standards "that should pertain to thy estate" as an earl.

[102] Radford's murder marked the beginning of a brief campaign[103]—a "range war"[38]—between the two sides, even more violent than had gone before; which, says Griffiths, turned the region "periodically into a private jousting-field".

[104] Bonville retaliated against Courtenay by looting the Earl's Colcombe manor;[2] says the historian John Gillingham, "on both sides houses were pllaged, cattle driven off, and plenty of plunder taken".

[110] "Moche people wer sleyn":[2] Although the engagement appears to have been somewhat inconclusive,[111] if anyone lost, it was Bonville,[102][112] who managed to escape alive,[10] although, suggests Hicks, dishonoured, as he had been the challenger.

[6] Courtenay, by his actions at St Albans, had earned the support of Henry's powerful Queen, Margaret, who was by now implacably opposed to the Yorkist party.

[119] The modern historians Roskell and Woodger in the History of Parliament suggest that throughout this period Bonville managed to conceal any sympathy for the Duke of York and remained "outwardly loyal to Henry VI".

[2] The historian Charles Ross has described Bonville during this period as "a veteran servant of the House of Lancaster, who had been promoted to his peerage by King Henry VI [and who] clung to the court he had always served".

[120] He swore to uphold the rights of young Edward, Prince of Wales against the Yorkists at the 1459 Parliament,[10] and in early 1460 he was commissioned to raise an army in the south-west.

[136] Bonville's and Courtenay's deaths prolonged the power vacuum in Devon, and, says the historian Malcolm Mercer, "a dominant source of authority in the area remained elusive thereafter".