M. Junkelmann, Reiter wie Statuen aus Erz, Mainz, 1996, p. 95, no. O 110; and H. Born and M. Junkelmann, Römische Kampf- und Turnierrüstungen: Sammlung Axel Guttmann, VI, Mainz, 1997, p. 103, pls. 77-78 (AG 709).
Cf. M. Junkelmann, op. cit., 1996, p. 46, pl. 90 for a discussion of the type and for a similar fragment from the Prähistorisch Staatsammlung, Munich; and H. Russell Robinson, The Armour of Imperial Rome, London, 1975, pp. 124-125, pls. 361-362 for the female mask type, Cavalry Sports type E.
The calvalry sports helmet, covering the face and resembling a theatrical mask, was worn by Roman auxiliary cavalry in equestrian exercises known as hippica gymnasia. Along with these elaborate helmets would be worn a special shield, embroidered tunic and possibly thigh-guards and greaves, all of which would contribute to the splendour of the display intended to impress the spectators. These displays most probably accompanied religious festivals celebrated by the Roman army and were also put on for the benefit of visiting officials. Arrian, a provincial governor under Hadrian, and the only source of information about the hippica gymnasia, describes how the horsemen were divided into opposing teams, taking turns to attack and defend. A small series of masks representing females survive. These most probably would have been worn by the team representing Amazons in re-enactments of the wars between Greeks and the Amazons, an unfailingly popular theme for Greek and Roman artists, and a good subject for display. Whether these hippica gymnasia were always associated with religious ritual is open to debate.