The Art of War in the Middle Ages (378-1515) is a concise yet ambitious survey of European warfare from the late Roman world to the threshold of the early modern age. Oman traces the changing balance between infantry, cavalry, fortification, and missile weapons, moving from Adrianople and feudal chivalry to the Swiss pikemen, English longbowmen, and the gunpowder transformations culminating around Marignano. Written in a lucid Victorian scholarly style, the book combines narrative clarity with strategic analysis, standing within the late nineteenth-century effort to make military history a rigorous historical discipline. Charles Oman, later Sir Charles Oman, was an Oxford historian and one of Britain's foremost military scholars. His training in institutional and political history, together with his lifelong interest in tactics and campaigns, shaped his attention to the practical mechanics of battle rather than mere romantic pageantry. Writing in an age fascinated by both medievalism and professional military reform, Oman sought to explain how armies actually fought and why tactical systems rose or failed. This volume is recommended to readers seeking a foundational interpretation of medieval military development. Though some conclusions have been revised by later scholarship, Oman's synthesis remains elegant, forceful, and historically influential.