The subject of this article is a uniform group of Roman military horse-trappings of the first century a.d. found at Xanten and now in the British Museum. They were included with brief and, it is fair to say, inadequate entries in H. B. Walters' Catalogue of 1899 where it was suggested, wrongly, that the trappings were from an ornamental cuirass. Since then there has been no attempt at a comprehensive publication, or proper explanation of their purpose. The four large roundels in the group have, it is true, been frequently mentioned in the study of so-called phalerae However, discussion of these pieces has consistently ignored the related groups of harness furniture to which they belong. If this fact is surprising, it is all the more so when we reflect upon their obvious importance for the study of Roman military equipment. The publication of the, in many respects, parallel finds from Doorwerth on the Rhine in Holland by J. H. Holwerda in the 1930s has recently been challenged by M. Brouwer. While Holwerda claimed to have substantial parts of no less than five sets of horse-trappings, Brouwer argues that the horse-trappings from Doorwerth are too much of a miscellany even to attempt a reconstruction of one set. Brouwer condemns, accordingly, the plaster reconstruction (FIG. I) that used to stand in the Bronze Gallery of the Rijksmuseum van Oudheden as inaccurate. The Xanten horse-trappings are, then, the most complete, single surviving set of Roman military horse-trappings of their kind. On the basis of comparison with grave reliefs, and on internal evidence, it is possible to offer here a reconstruction of the original harness. On the basis of inscriptions punched into the trappings themselves, it is possible to speculate on the ownership of the trappings and the significance they held for their owner. Not the least interesting of these graffiti is the inscription PLINIO PRAEF(ECTO) EQ(UITUM) punched into the face of one of the large roundels (A3). More than one scholar has seen here an explicit reference to the historical C. Plinius Secundus, commonly known as Pliny the Elder.