Among the treatises on logic left to posterity by the xivth Oxonian philosopher Ralph Strode, is a treatise on those formal exercises, typical of Scholastic logic, called Obligationes. In the preface to this treatise, Strode introduces the genre by developing a spectacular martial metaphor in which the ars obligatoria is compared to the ars dimicandi, in other words to the art of combat, and more specifically to fencing. This contribution is divided into two parts: in the first, Pascale Bermon transcribes the Prologue to Strode’s Obligationes from the Venice edition of 1507, followed by a French translation; in the second, Hélène Leblanc offers a commentary on this text.