Upon receiving these letters, the rebels withdrew their homage and fealty to the king and fighting was now all-but inevitable.
In terms of numbers, Simon de Montfort had about 500 cavalry (both knights and mounted serjeants) at his command, with perhaps up to 5000 foot soldiers. The king commanded around 1500 cavalry and probably a few more infantry than de Montfort: it is likely that these numbered less than 8000.
Clearly outnumbered, and in order to gain surprise and an advantage, Simon de Montfort moved his men during the night of the 13th/14th of May, where they "traversed the dark covering of the woods", and gained the high ground to the west of Lewes, by way of an ancient trackway through Boxholte up onto the Downs.
Here they proceeded south-east along the edge of the Downs until they reached a flat area of ground, from where de Montfort could look over the crest and see Lewes, dominated by both the castle and the priory. It is likely that his forces were all in place when the sun rose at 4.00 am on the 14th May.
It is also likely that this was the point at which de Clare was knighted (de Clare had been waiting to inherit his fathers' lands in the Marches for some time).
Then Simon de Montfort went on to address the army. He said that their cause was just, and that they were fighting for the kingdom of England and the honour of God.
Sins were confessed and white crosses donned, to signify their holy cause; and, as importantly, to aid recognition in the heat of battle that was to follow.