In August 1643, Charles I and his army surrounded Gloucester but withdrew to avoid a confrontation when Robert Devereux, Earl of Essex, arrived the relieve the city. Royalist forces now moved to block the Parliamentary army's return to London.

Charles I, with 8,000 foot soldiers and 6,000 cavalrymen, set up defensive positions to the west of Newbury. Prince Rupert was in command of the cavalry and Jacob Astley the infantry.

Robert Devereux arrived with 10,000 foot soldiers and 4,000 cavalrymen. Although he arrived after the Royalists he managed to secure the best ground at Round Hill. An attack led by John Byron and his Cavaliers failed to capture the position from the Roundheads.

The Royalists ran short of ammunition and that night, despite the protests of Prince Rupert and John Byron, the king decided to withdraw to Oxford. This enabled Robert Devereux and his Parliamentary army to return to London.