John de Vere, born 14 August 1499, was the second but only surviving son of Sir George Vere and his second wife, Margaret, the daughter of Sir William Stafford of Bishop's Frome in Herefordshire by Elizabeth Wrottesley, daughter of Hugh Wrottesley, esquire. Sir George Vere had been intended for the priesthood, and in 1459, when he was only sixteen, his father, John de Vere, 12th Earl of Oxford, appointed him to a benefice in Lavenham, Suffolk. However both the 12th Earl and his eldest son and heir, Aubrey de Vere, were executed in February 1462, and George then became second in line to the earldom as the potential heir to his brother, John de Vere, 13th Earl of Oxford. Instead of George, his younger brother, Richard, became a priest, and in 1459 George married, as his first wife, Margaret Talbot (d. December 1472), the sister and coheir of Thomas Talbot, 2nd Viscount Lisle (d. March 1470). He fought at the Battle of Barnet on 14 April 1471, and was with his elder brother, John de Vere, 13th Earl of Oxford, when he seized St. Michael's Mount in Cornwall on 30 September 1473. Sir George Vere was attainted in Parliament in early 1475, together with his brothers, John and Thomas. Ross states that Sir George Vere was never officially pardoned, although Richardson states that his attainder was reversed when King Henry VII came to the throne in 1485.