NM-15 Norman Casualty, Norman Army
We know that the English forces were deployed in a dense shieldwall formation at the top of a slope, (which newer sources suggests was Caldbec Hill), with their flanks protected by woods, and with marshy ground in front of them.
What is known about the Norman deployment, is that Duke William appears to have arranged his forces in 3 groups or “battles”. The left “battle” consisted mainly of Bretons, and was led by Alan The Red. The Centre was held by the Normans, under direct command of the Duke, and the right was commanded by William Fitzosbern and Eustace II of Boulogne, and consisted of Frenchmen. and mercenaries from Picardy, Boulogne and Flanders.
The front lines of the invading force were made up of archers, with a secondary line of foot soldiers armed with spears and swords. The cavalry was held in reserve. The Norman disposition of forces implies that the plan was to open the battle with archers, weakening the enemy with arrows, followed by infantry who would engage the shieldwall in close combat. The infantry would create openings in the English lines that would then be exploited by cavalry charges.
It is believed that the early barrage of arrows, probably had very little effect on the English shieldwall, due to the higher position of the English on the ridge.