Though many miles apart, it was the march by the Earl of Essex to Gloucester and his subsequent return to London that brought him into conflict with Royalist forces at Newbury. If Essex lost then the future would look very bleak for parliament. The battle was a direct result of the siege of Gloucester by Charles I. Battle of Newbury I 20th September 1643. On the morning of 20th September 1643 the battle of Newbury was fought between parliament's main field army under the Earl of Essex and the main Royalist army in the south, with both Charles I and Prince Rupert present. To the English Civil War index. Battle: First Battle of Newbury War: English Civil War Date of the First Battle of Newbury: 20 th September 1643 Place of the First Battle of Newbury: On the western approaches to Newbury in Berkshire. The first battle of Newbury took place September 20 th 1643. The next battle in the English Civil War is the Battle of Cheriton. The previous battle in the English Civil War is the Storming of Bristol.