This article explores the reasons why mounted men-at-arms might dismount to fight, individually or collectively, focusing mainly on the late medieval period. The interface between mounted and dismounted combat is examined together with the factors that led either to success or failure. The grounds for dismounting were varied, but the handling of the horses and concern for their safety remained a continuous thread that impacted on the course of events and frequently decided the outcome of engagements. Although generally associated with English armies of the Hundred Years’ War, dismounting to fight was, in fact, a well-established practice throughout Western Europe. Yet, no matter how courageous or experienced, when those on foot faced cavalry, the outcome could never be certain, hence the deployment of anti-equestrian devices, such as pits, caltrops, and stakes, to try to equal the odds. The most effective defense against cavalry, however, was the judicious use of terrain, particularly hedges and vineyards, and an analysis will be made of how these specific features were utilized. The armor of the period reflected a nation's fighting preferences and in the most successful armies, men-at-arms transitioned easily between being on horseback or on foot and combined well with archers and other arms. The loss of this flexibility caused significant problems, as the English discovered to their cost.