The parliamentary army was posted on a ridge of ground lying south of the wide expanse of moorland, now all enclosed and cultivated, which stretched nearly to York. At the northern foot of this ridge, which was covered at the time of the battle with rye full grown though not ripe, runs a lane joining two hamlets, Long Marston and Tockwith, about a mile and a half apart. North of this line the moor rose, quite open and bare, though there was a wood a mile or so to the northwards. The moor was divided from the lane by a ditch, which has since disappeared, and therefore cannot be placed with accuracy. A little way from this ditch Rupert drew up his line, so near to it in fact that a battle must ensue, as neither side could possibly withdraw in safety. At the same time the ditch was a sufficient obstacle to make both sides somewhat reluctant to begin. Neither side seems to have thought it worth while to attempt to utilise the enclosures of Long Marston or Tockwith: indeed they could not have been occupied without departing from the established tactics of the day, which drew up the infantry in the centre, placing cavalry on each wing. Obviously the enclosures would have been fatal to the full use of the cavalry.
The threefold division of the parliamentary army was naturally retained in the order of battle. Manchester's troops were on the left of the line, Cromwell's cavalry reinforced by three Scottish regiments under David Leslie being on the flank, and the infantry commanded by Crawford to their right. In the centre were part of the Scottish infantry under Baillie; to their right Lord Fairfax commanded his own infantry, with the rest of the Scots in reserve behind him. The extreme right was occupied by Sir Thomas Fairfax's horse, again with a reserve of Scottish cavalry in rear. The numbers seem to have been about 19,000 foot and 7600 horse, the royalists having some 3000 less infantry but being equally strong in cavalry. The proportion of cavalry to infantry is enormous if measured by modern standards, though it was exceeded in some other battles of the war. This was of course natural, in view of the superior value of cavalry in action, as compared to the ill-armed infantry of that age. The royalist line was formed in a similar fashion. Rupert's infantry was on the right, Newcastle's on the left; the prince commanded in person the horse on the right wing, Goring those on the left. It seems strange to a modern reader, who habitually associates the idea of marked uniform colours with the soldier's appearance, to find that Newcastle's infantry attracted special notice as the Whitecoats, because the marquis had clothed them alike in undyed cloth, and that the parliamentary soldiers all wore white ribbons or paper in their hats in order to recognise one another. An equally marked contrast with the warfare of to-day is to be found in the fact that both sides, having twenty or thirty guns, merely used them during the afternoon for a little futile cannonading, and ignored them entirely in the real battle.