When Edward I spent the winter of 1294–95 in the crowded confines of Conwy castle, there was a crisis. The wine ran out, all save one small cask, and that was reserved for the king's own use. Sensibly, Edward ordered that its contents be distributed among his men, a gesture which surely did much for morale. Castles needed much more for defence than keeps, gatehouses and strong walls. Well-equipped garrisons were required, but if they were to be effective, they needed food and drink. ‘Lytel is worth the strengthe of the walles of a castel, how wel that hit by garnysshed of al deffensable thynges, what lacke a faulte of vytaille is there yf hit be besieged.’ Caxton's translation of Christine de Pizan was very much to the point. The evidence of what castle garrisons had to eat provides one, admittedly narrow, window into the reality of service in war in the Middle Ages, a reality which Maurice Keen has done so much to illuminate. The topic is not one that has received much attention from the historians of castles, for whom the military aspects of their subject are becoming increasingly unpopular, as they emphasise the symbolism of power, rather than the reality. The question of food supply, however, should be a significant element in any analysis of the role of the medieval castle. For a fortification to play an effective military role, it needed to be able to hold out against blockade. A castle without sufficient stores, no matter how massive its walls or how powerful its gatehouse, was hopelessly vulnerable.

In normal conditions the provision of food for castles presented no particular problems. Manning levels were usually low, and demands therefore not heavy. Most castles never underwent a siege, and arrangements to provide adequate supplies for wartime conditions were simply not required. Where a castle served as a major residence, the issues were those that faced any noble household, and diet would have been no different within a castle than without. Very many castles were manorial centres, and so had land that either produced much of what was needed, or brought in rents that could be used to purchase food.