"My work may be garbage but it's good garbage." Mickey Spillane
I’m doing these in the order that they happened while I’m reading A Brief History of Medieval Warfare: the Rise and Fall of English Supremacy at Arms 1314 – 1485 by Peter Reid.
Edward III was king of England at this point, a twenty year old man heading for his first battle. No doubt, he received a lot of input from his military advisors, but ultimately the final decisions belonged to Edward. He besieged the town of Berwick, forcing the Scots to march to the relief of the town, and then set up to deal with them.
The terrain was two hills, Halidon Hill where the English deployed their forces; and Bothul Hill. Between the two hills was a wide bog. The Scots under Archibald Douglas, concerned about the possibility of being flanked by the English, chose to march the long way around Bothul Hill. Bothul Hill is taller than Halidon, so that might have masked some of the Scottish formation.
The English had learned a lot from the Battle of Bannockburn. Out of 20,000 men, 8,000 were archers.
Armor has gotten heavier and more complex for the mounted knights, and Reid postulates that full armor would have been too heavy for the Scots to make a 1,000 yard dash across the bog on foot. The boggy terrain sitting between the two hills would not work well for bringing the heavy cavalry through.
The Scots dismounted, formed their schiltroms, and came at the English on foot. Reid estimates that the English longbowmen, deployed on the flanks of the army, were able to loose about thirty arrows each in the three to four minute arrow storm that played havoc with the Scottish troops. The schiltroms that had made a mess of the English at Bannockburn were shredded. The Scots retreated and the English infantry and cavalry went after the survivors with orders to take no prisoners.
As 50ftAnt remarked in the comments to the previous military post, choosing your ground is important. At Bannockburn, the Scots had time to choose where to deal with the English. At Halidon Hill, the English had already set up entrenched positions for their archers and such, and they had the high ground.