God's Fury, England's Fire_ A New History of the English Civil Wars - Michael J. Braddick [175]
As it turned out, however, the royalists did not press home this advantage. The Yorkshire levies refused to move south and Newcastle was forced to besiege Hull, while Hopton’s Cornish levies similarly wanted to stay at home to protect their county from the garrison at Plymouth. Welsh troops refused to cross the Severn until Gloucester was taken. Since neither the northern nor the western armies were willing to advance further the real question was what to do with the armies in central England. With Waller beaten and back in London the way was clear for an advance on the capital, but Prince Rupert was instead sent to take Gloucester. The Parliamentary commander there, Massey, was thought to be wavering in his loyalty to Parliament, and certainly Gloucester was no more defensible than Bristol. Taking Gloucester would cement the royalist position, clearing communications between Oxford and south Wales and giving control of the Severn Valley. But posterity has blamed the royalists for failing to move decisively on London. As on the other side there was division over war aims too: between those who simply wanted to win the war and those who wanted to win the war in order to preserve the constitutional settlement of 1641, those who ‘wished to carry on the war with a view to the eventual peace’. This division erupted between Prince Rupert and the Earl of Hertford and between Prince Maurice and the Earl of Caernarvon over their conduct following victories in Bristol and Dorset. There were military arguments in favour of the more cautious strategy and it is not clear that the royalist armies were really in a position to advance at this moment. But the relatively conservative decision to move on Gloucester rather than London probably reflected the influence of moderate counsels as much as military considerations. In any case it was this decision which probably saved Parliament’s bacon: if the three royalist forces had pushed on in concert towards London victory might well have been possible.65
When Rupert arrived before Gloucester, Massey refused to surrender and this led to a second crucial decision – to lay siege to the city rather than storm it. This decision arose, it is said, from Charles’s own distaste for the human costs of the storming of Bristol, and to that extent it can be admired, but from a military point of view it was a questionable judgement. Gloucester could probably have been stormed quite quickly, whereas a siege tied down a large number of troops and gave Parliament time to levy a relieving force. On 27 August, Essex led out an army of 15,000 men, including men of the London Trained Bands, which entered Gloucestershire at Stow-on-the-Wold on 4 September. There an attack by Rupert failed and Essex reached Gloucester on 5 September. It was not a moment too soon, since Massey had only three barrels of powder left when they arrived, but their arrival had an immediate effect. Charles, unwilling to be caught between Essex’s army and the Gloucester forces, withdrew rather than risk losses and Essex was able to raise the siege on 8 September. There then began a race to prevent Essex reaching London. This relieved an appalling position, and boosted morale, but military advantage still lay with the royalists. Rupert still intended to engage Essex, but not in front of a hostile city, and further west royalist successes had continued as Barnstaple, Bideford and Exeter surrendered between 28 August and 4 September. West of Poole only Lyme, Plymouth, Dartmouth and Wardour Castle now held out for Parliament.66
Between late February and late April important measures had been taken to stiffen the parliamentary alliance, but the military tide had certainly not turned.