According to Gravett and fellow military enthusiast Trevor James Halsall, Somerset's decision to engage the Yorkist army on this plateau was sound. Defending the ground just before Towton would block any enemy advance towards the city of York, whether they moved along the London–Towton road or an old Roman road to the west. The Lancastrians deployed on the north side of the dale, using the valley as a "protective ditch"; the disadvantage of this position was that they could not see beyond the southern ridge of the dale. The Lancastrian flanks were protected by marshes; their right was further secured by the steep banks of the Cock Beck. The width of their deployment area did not allow for a longer front line, depriving the Lancastrians of the opportunity to use their numerical superiority. Waurin's account gave rise to the suggestion that Somerset ordered a force of mounted spearmen to conceal itself in Castle Hill Wood, ready to charge into the Yorkist left flank at an opportune time in battle.