Progress in actually fighting the Shropshire royalists was initially slow – not least because the regional parliamentarian commander, Basil Feilding, 2nd Earl of Denbigh was the object of accusations of disloyalty which he shook off only with difficulty. However, with the help of Sir William Brereton of Cheshire the Shropshire committee seized a foothold in the county at the unfortified market town of Wem, around the end of August 1643. Some of the committee took up residence there, taking with them as temporary chaplain the puritan minister Richard Baxter, who was recruited by Mackworth and Thomas Hunt at Coventry: although Mytton was the military governor at Wem, Baxter referred to the parliamentarian garrison as "Colonel Mackworth's troop." In October the small garrison, with trenches still only partly dug, drove off a full-scale royalist attack, under Lord Capel. An uprising of the townspeople, including women armed with pans, was credited with turning the tide and a popular rhyme declared: Mackworth was present during the royalist assault and seems to have taken part in the fighting. The Wem outpost remained under constant threat and only some of the committee risked their own lives by remaining there. Sir John Corbet was mostly in London. Mackworth seems to have been active in the area, as a commissioned captain in the parliamentary army, but was sometimes in Coventry or in London. In December Mackworth, Mytton and others sent a letter from the committee at Wem to the Commons, suggesting that both were present at what was a dangerous time. A damaged letter from the same month, preserved in the state papers and complaining about depredations of the Parliamentarians around Hodnet, name Mackworth, Mytton, Lloyd and Thomas Hunt as "the chief men with us of  the Committee." Later in the month Mackworth went to London, where he was due to make depositions against Laud before a House of Lords committee in January 1644. These particularly related to Laud's interference with the town's charter, in a dispute between the town and William Beale, Master of St. John's College, Cambridge, and in the appointment of the head of Shrewsbury School. Meanwhile, the situation in Shropshire became desperate as numerous experienced royalist soldiers, redeployed during a lull in the Irish Confederate Wars, entered the country via Chester. Robert Corbet and Andrew Lloyd, committee members who remained at Wem, wrote to Mackworth, asking him to "represent our forlorne condition to the Parliament, for whom we have desperately engaged our estates and lives."