horse armour in the Byzantine writing of this time is by Choniates and is a description of the front ranks of the cavalry of the Hungarian army at the Battle of Sirmium. However, earlier military treatises, such as that of Nikephoros Ouranos, mention horse armour being used and a later, 14th century, Byzantine book illustration shows horse armour. It is therefore very likely that horse armour continued to be used by the Byzantines through the Komnenian era; though its use was probably limited to the very wealthiest of the provincial kataphraktoi, aristocrats serving in the army, members of some guards units and the imperial household. The construction of horse armour was probably somewhat varied; including bardings composed of metal or rawhide lamellae, or soft armour of quilted or felted textile. The historian John Birkenmeier has stated: "The Byzantines, like their Hungarian opponents, relied on mailed lancers astride armored horses for their first charge." Equipment: Artillery The Komnenian army had a formidable artillery arm which was particularly feared by its eastern enemies. Stone-firing and bolt-firing machines were used both for attacking enemy fortresses and fortified cities and for the defence of their Byzantine equivalents. In contemporary accounts the most conspicuous engines of war were stone-throwing trebuchets, often termed helepolis (city-takers); both the man-powered and the more powerful and accurate counterweight trebuchets were known to the Byzantines. The development of the trebuchet, the largest of which could batter down contemporary defensive walls, was attributed to the Byzantines by some western writers. Additionally, the Byzantines also used long range, anti-personnel, bolt firing machines such as the 'great crossbow,' which was often mounted on a mobile chassis, and the 'skein-bow' or 'espringal' which was a torsion device using twisted skeins of silk or sinew to power two bow-arms. The artillerists of the Byzantine army were accorded high status, being described as "illustrious men." The emperor John II and the generals Stephanos and Andronikos Kontostephanos, both leading commanders with the rank of megas doux, are recorded personally operating siege engines. Troop types The Byzantine Empire was a highly developed society with a long military history and could recruit soldiers from various peoples, both within and beyond its borders; as a result of these factors a wide variety of troop types were to be found in its army. Infantry With the notable exception of the Varangians, the Byzantine infantry of the Komnenian period are poorly described