Charles advanced as far as Brentford, but the troops drawn out for the defence of London were too strong to be attacked, and he withdrew to Oxford, and entered on useless negotiations for peace. When active hostilities were resumed in the spring of 1643, all went favourably for the king. John Hampden, one of the most important leaders in the House of Commons, was killed in a skirmish: a series of successes in the field gave the whole south-west, with the important exception of Plymouth, into royalist hands: a victory at Atherton Moor drove Fairfax into Hull, and made the king master of all the rest of Yorkshire. Had Charles boldly marched on London, it is possible that the citizens in their dismay would have submitted. But Charles was hardly the man to take an audacious resolve; and it would have been audacious, even if no stronger word be applicable, to advance on London with his own immediate forces. His right wing, so to speak, was tied to the west by Plymouth, the garrison of which, if left unbesieged, would soon have revived the partisans of Parliament in the west. His left wing was still more closely fettered by the necessity of observing Hull. Moreover behind the king lay Gloucester, well garrisoned, and interrupting at a vital point, the lowest bridge on the Severn, free communication between the royalists of the south and west. Ordinary military judgment pointed out the capture of Gloucester as the most useful enterprise he could attempt, while waiting for the co-operation of Hopton from the west, of Newcastle from the north. The Parliament realised the supreme importance of Gloucester, and Essex, with an army consisting largely of the London train-bands, marched to relieve the place. Charles was obliged to raise the siege, and on his return to Oxford fought with Essex the bloody and indecisive battle of Newbury. The tide of royalist success had been stemmed, but no more. The outlook for the parliamentary cause seemed so gloomy that Pym, their greatest statesman, negotiated with his dying breath, at the price of important concessions to the Presbyterian spirit, for the assistance of the Scots for the next campaign. Things however were in reality less black than they seemed: in the eastern counties not only had their cause completely triumphed, but an army was being organised which was to turn the scale in the next year. This army was commanded by the earl of Manchester, under whom was Cromwell at the head of the cavalry, which was the specially important arm. In it the ideas which Cromwell had been the first to act on were definitely carried out. To quote the description of it sent to London by an admiring correspondent of a newspaper—"Neither is his army so formidable in number as exact in discipline; and that they might be all of one mind in religion as of resolution in the field, with a severe eye he hath looked into the manners of all those who are his officers, and cashiered those whom he found to be in any way irregular in their lives or disaffected to the cause. This brave army is our violets and primroses, the first-fruits of the spring, which the Parliament sends forth this year, for the growth of our religion, and the re-implanting of this kingdom in the garden of peace and truth."