At Stirling Bridge, Wallace had deployed his men in the revolutionary tactical formation known as the shiltron. This was a circular formation of about a thousand men which could move slowly without losing order. When attacked by cavalry, the men on the outside of the shiltron knelt down and braced their spears against the ground with the sharp points projecting outward. This formed an impenetrable hedge of spikes from behind which the rear ranks could thrust at enemy cavalry. The previously unstoppable charge of heavily armoured knights could thus be halted.
At Falkirk, Wallace again deployed his main body in shiltrons, formed up on the slopes in front of Callendar Wood. The few cavalry he had were placed behind the shiltrons and the archers interspersed in pockets among and between the shiltrons. His plan was to lure the English cavalry into charging against the shiltrons where they would be halted by the spears, shot down by the archers and then tumbled into defeat by a counter charge from his own knights. With the English knights defeated, Wallace hoped, the rest of the English would retreat as they had done at Stirling Bridge. To further ensure the charge of the English knights was disrupted, Wallace placed his men behind a small burn which had marshy banks.
The tactics of the various elements of the English army would be much the same at Falkirk as at Stirling Bridge, but with one crucial difference. Up until this time it was usual to spread the archers evenly through the army and rely on their skill at aiming to shoot down enemy troops. But Edward had been listening to his commanders who had been defeated at Stirling Bridge and he knew the key to victory was to defeat the apparently impervious shiltrons.
Edward reasoned that the shiltrons were invulnerable to a traditional charge of armoured knights, but only so long as the infantry formation held firm. Once the formation was disrupted, a cavalry charge would succeed. He knew that the archers at Stirling Bridge had tried to pick holes in the Scots ranks, but had failed. Edward decided to try a new archery tactic.
He ordered his Welsh archers not to bother aiming at individual enemy soldiers at all. He reasoned the shiltrons were so closely packed with men that an arrow hitting roughly the right area was bound to find a target. Edward told his men to concentrate on the speed with which they could shoot, not on accuracy. Then he bunched his archers into large formations of over 2,000 men each. So many men shooting rapidly in the same direction would create an ‘arrow storm’ which would lash an area of ground like a sudden storm of rain.