Thomas Courtenay was 26 years old when his father died on 3 February 1458. The Courtenay family were among the greatest magnates of the south-west, especially in
Devon, where they had their greatest concentration of estates and dominated a tightly-knit affinity among the local
gentry. In the mid-fifteenth century their local supremacy had been challenged by
William, Lord Bonville, leading to a
violent feud which culminated in Bonville's defeat by Thomas's father at
Clyst Heath in 1455. That Earl, frequently in trouble with the law for his violent behaviour, had been among the closest allies of the disaffected
Richard of York in the early 1450s, but a wedge was driven between York and the Courtenays when Bonville became a client of the leading
Yorkist magnate
Richard Neville, Earl of Warwick. When the first major phase of the
Wars of the Roses broke out in 1459, Earl Thomas remained loyal to
Henry VI. After the Yorkists seized power and captured King Henry in 1460, he joined other south-western aristocrats including
Henry Beaufort, Duke of Somerset in raising a
Lancastrian army, which went to join the forces being gathered by the queen,
Margaret of Anjou, in northern England. The Bonville family, fighting on the Yorkist side, were wiped out during the ensuing fighting, but the Lancastrians were decisively defeated in the
Battle of Towton on 29 March 1461. Courtenay was captured in the battle, and was beheaded at
York on 3 April. He was
attainted by
Parliament in November of that year, depriving his heirs of the earldom of Devon, the barony of Courtenay and his estates. Courtenay's younger brother, Henry, had been granted several manors by King
Edward IV on 27 July 1461, including
Topsham, and these manors were also forfeited by his elder brother's attainder. Henry himself was beheaded at Salisbury on 17 January 1469. ==Marriage==