The trappings of war were everywhere in late medieval England. Knightly families prided themselves on the military insignia of their coats of arms. Tombs showed knights in full armour. Seals displayed lords mounted on their chargers. Even a water jug might take the form of a fully armed and mounted knight. The concept of war was glorified in a world of chivalric values. War was not, however, a matter of colourfully caparisoned knights riding to battle in a glamorous cavalcade. It was a highly complex business. Resources were mobilised on a massive scale to ensure that armies were properly supplied and financed. Bankers gambled as they lent to competing monarchs. Fortunes were won and lost, notably in the ransom market that followed success on the battlefield. War was also a powerful engine for social change; fortunes could be lost and won, not only by those who fought, but also by those who financed and supplied the campaigns.

The intensity of war varied considerably. In the early thirteenth century England was a backwater in military terms. King John lost his continental possessions with the exception of those in south-western France, and by the end of his reign there was a very real possibility that Capetian France would absorb the English monarchy. Under his successor Henry III expeditions to France were few, and did little more than defend existing English possessions; there was no realistic hope of recovering Normandy. Civil war in the mid 1260s was fierce, but brief.