The light lance or lancegay was one of the most ubiquitous weapons used throughout centuries of warfare in Europe and beyond, from ancient times well into the modern era. This article traces the development of the weapon during the medieval period in its broadest sense, though drawing on its earlier and later manifestations. It offers a detailed analysis of a major category of weapon that has received far less attention than more glamorous but shorter-lived arms such as the heavy war lance and the longbow. It demonstrates that the maneuvers of the light lance and the tactics commonly associated with Napoleonic and later periods were familiar to medieval warriors and outlined in contemporary literature. The lancegay was a flexible and enduring weapon, favored by all classes of society, that could be deployed quickly both on horse and foot. Despite some variation in nomenclature, it is possible to demonstrate how the lancegay was utilized by different groups during and beyond the medieval period. Its carriage and manipulation are examined together with the tactics and riding skills that enabled it to achieve its full potential within a light cavalry role.