Thurstan, Archbishop of York, had been too ill to travel with the army. Command was possibly given to Walter Espec, Sherrif of York, or William of Albemarle, though on this the accounts are not clear.
However there were also with them a number of barons from the region and it has been suggested that Sir Robert de Ferrars, who had some experience of warfare in France and would become one of the most able soldiers of his generation, had a significant role in the tactical decisions. Others included Robert de Bruce; Bernard de Baliol; Adam de Bruce; Gilbert de Lacy; Walter de Gaut; Roger de Mowbray; William de Peverill; Robert de Stuteville; Richard de Courcy; William Foassard.
The barons in the region gathered their followers, while Stephen had also sent Bernard de Balliol with a small body of knights to support the army. In Thirsk the army was joined by Sir Robert de Ferrars, who had raised the nobility of Derbyshire and Nottinghamshire to march north with him. The local militia had also been raised by the parish priests in the region who led all the able bodied men of their parish to Thirsk, where the army was to assemble.
The mounted knights were probably few in number but they were supported by a far larger number of men at arms. These retainers of the feudal lords were well armed and armoured professional soldiers. It has been suggested that together they comprised some 6,000, though all such calculations are based on dubious foundations. In addition there were archers with longbows perhaps not too dissimilar from those with which the English forces were to so dramatically destroy French armies in the 14th and 15th centuries. It has been suggested that there were as many as 1000 archers. The local militia may have been poorly trained and armed largely with makeshift weapons such as axes and scythes, but their numbers may have been substantial, though suggestions of 5-10,000 is undoubtedly an exaggeration.