In January of this year Rupert had captured Aylesbury, and early in March he set out to relieve Newark which had been invested by the Parliament. The siege was raised, and the besiegers, who were commanded by Sir John Meldrum, were forced to capitulate; but Rupert had to return his troops to the garrisons from which he had borrowed them, and almost without an army he marched back to the Welsh border, where he occupied himself with raising fresh troops to go to the assistance of the Earl of Newcastle.
As soon as his intentions for the north were known, the Earl of Derby endeavoured to persuade him to march by way of Lancashire in order to relieve Lathom House. The besieged Countess must have written to her husband in a very different tone from that of her defiant answers to Rigby; indeed if the Earl of Derby did not unduly exaggerate the position of the garrison, they must have been in imminent fear of being compelled to surrender. The petition was, however, seconded by the Lancashire royalists, and the Earl of Derby promised that if Lathom were relieved he would aid Rupert's further march with 2,000 men and a considerable sum of money. It was pointed out that the towns of Liverpool and Warrington were but weakly garrisoned, and that the reconquest of Lancashire would be a great gain for the King's cause in the north of England, "the rebellion in those parts being wholly supported from there." Liverpool would be of immense use as the port towards Ireland, and Derby and Prince Rupert had already discussed over the map the possibility of reducing it.[138]
Sir John Byron, the royalist Governor of Chester, was persuaded to support the scheme; and the Earl of Derby having personally written to the King urging its desirability, Charles' approval was given. The prospect of invasion had caused great consternation among the Lancashire Parliamentarians as early as the middle of March;[139] but it was two months after that before Rupert was able to move. Drawing his forces together he began his advance towards Yorkshire about the middle of May. On the 18th the royalists moved from Holt, Malpas, and Whitchurch, to a more easterly position at Market Drayton; and next day they crossed the River Weaver, and advanced to Audlem and Bruerton which are just over the Cheshire border. A thousand Parliamentarian troops marched out of Nantwich as far as Hatherton, but Rupert was not anxious to fight and fell back to Audlem. (Monday, May 20th.) It was feared that he would lay siege to Nantwich, but he passed to the east of that place, and on Tuesday, May 21, his troops were quartered about Haslington and Sandbach, while Rupert himself stayed at Betley. On May 24th the march to Lancashire began, and the royalists lodged at Knutsford, which is only ten miles from the Lancashire border; the following day they advanced to Stockport, only seven miles distant from Manchester. Prince Rupert's forces were estimated at 8,000 or 10,000 men, mostly cavalry, and they were said to have 50 guns. At Stockport Colonels Mainwaring and Duckenfield were posted with about 3,000 men to oppose his advance, but they seem to have made very little resistance, and after a short skirmish they broke and fled towards Manchester, leaving 800 prisoners. The royalists occupied Stockport, and were joined there by some of Newcastle's cavalry from Derbyshire. Rupert left some of these to garrison Stockport, and moved on into Lancashire with the main body of his army.[140]