Patri has been called the midwife of modern historical European martial-arts studies, having been the source of reproductions of early combat treatises relied on by practitioners around the globe. His early training in the sword was provided by his mother, Julia Jones, first U.S. women's intercollegiate fencing champion in 1929 and professional coach until her death in 1993 at age 84.

Patri received his doctorate in 1982 in the History of Science from Harvard University, writing his dissertation on the work of Isaac Newton's seventeenth-century rival, Robert Hooke. In addition to providing the source texts that introduced many researchers to historical European martial arts, he was personally involved in the reconstruction of Renaissance and nineteenth-century western combat techniques for more than a decade.

He, with Jeffrey Forgeng and Paul Kenworthy, was one of the founding members of the Higgins Armory Sword Guild and with them gave the first combat demonstrations at the Higgins Armory Museum, as well as teaching classes in the rapier-play of Giacomo di Grassi and in Alfred Hutton's sabre system. His interest in historical movement included, in addition to fencing and bayonet drill, the art of social dance. He trained in Renaissance dance for many years with Dr. Ingrid Brainard and was for almost twenty-five years co-director of The Commonwealth Vintage Dancers, a nineteenth-century dance performance troupe, teaching at dance conferences and workshops in the U.S. and in Europe. This placed him in a long tradition of students and masters active in both fencing and dancing.

He was a noted historical re-enactor, especially well known for nineteenth-century portrayals, both as a member of the Salem Light Infantry (Salem Zouaves) American Civil War re-enactment unit, which he founded with Paul Kenworthy, and as a civilian re-enactor, and was an expert on the clothing of that period. Patri was from its early days prominent in the Society for Creative Anachronism, in which he was known as Baron Sir Patri du Chat Gris. He was a knight of the SCA; belonged to the Orders of the Pelican, the Laurel, and the White Scarf; was a court baron; and was for many years the Baron of Carolingia.

Patri worked, before its dissolution, at Dragon Systems, and later worked again with Janet Baker at the Dibner Institute for the History of Science and Technology, located at the Massachusetts Institute of Technology.