How maritime supply sustained medieval armies

Naval power supported English armies moving north into Scotland, while Scottish forces heading south also relied on maritime supply. English campaigns in France moved repeatedly through coastal and inland river ports. Armies foraged to reduce their logistical burden, but drink, arrows, and other necessities could not always be obtained from the surrounding countryside. Living off the land therefore reduced the supply problem without eliminating it. Those requirements help explain why an admiralty function remained necessary even where surviving appointment records are incomplete.