As national politics became increasingly divided during the 1450s, Oxford did not immediately take sides, although he was a member of the council while the Duke of York was Lord Protector in 1453–54 during Henry VI's period of mental breakdown, and on 28May 1454, together with 6 other peers and his brother, Sir Robert Vere, undertook to keep the seas for three years. In May 1455 he and the Duke of Norfolk both arrived a day too late to take part in the Battle of St Albans. It was not until 1459 that Oxford committed himself to Margaret of Anjou against the Duke of York. In December of that year and in April 1460 he was appointed to lead anti-Yorkist commissions of array in Essex, and by May 1460 his eldest son, Sir Aubrey Vere, who had recently married Anne, the daughter of Humphrey Stafford, 1st Duke of Buckingham, was reported to be 'great with the Queen'.