As much as military campaigns and battles are the product of military strategy, tactics and the intent of the commanders, in some ways it can also be subscribed simply to logistics. This is particularly true in Pre-modern History.
In a unique study of Alexander’s campaigns, Engels aligned the speed of the army, all delays, and strategic choices to the logistical necessities of moving 40-100,000 men and animals across mountains, deserts and all manner of terrain. While there is some opposition to his conclusions, it is a worthy endeavour.
I drew parallels to this work when reading the later books of Herodotus where Xerxes purportedly led nearly two million people across the Hellespont and down through Greece. Even if he led just a fraction of that number, assessing the speed, movement and strategic choices in light of the logistic nightmare before him–and in particular that of fresh water, would be worthwhile.
In particular withdrawing from Attike after the first harvest they destroyed (or harvested themselves) in 479, and then returning in 480 around harvest time again. Further, since he divided his force between Ionia (largely because they could have revolted again–and did so after the Battle of Mykale), Thrace and Thessaly, while dismissing some portion of it entirely following Salamis, Xerxes enabled his armies to function effectively, guard all its territory, including the satrap that was Thrace and Macedonia, and, most importantly, feed them.
This is not to say that all decisions are made based on the ability to feed the troops, but the truism that soldiers fight on their stomachs exists for a reason. Certainly how the troops were to be fed must be accounted for when thinking about overarching campaign strategy and movement.