The alae of the auxilia are the imperial army’s first rate cavalry units. Their training is excellent and extensive, their equipment makes them multifunctional.
New auxiliary cavalry wings can be formed in all provinces of the Imperium Romanum, where the local population is practicing horse breeding and riding in a degree to support such a move.
The alae of the auxilia are the imperial army’s first rate cavalry units. Their riders wear lorica hamata (chain mail) or lorica squamata (scale) armour, iron or bronze helmets and large hexagonal or oval shields for protection, while everyone is armed with a sword, a hasta lance and several iacula, light javelins. The helmets they wear are still from the same type as the legionary infantry’s gear, either variants of the Coolus bronze or iron imperial Gallic helmets, and less than optimal for cavalry warfare. Especially the large neck guards can be disasterous if the rider falls from his horse. In a few decades, in the first half of the 1st century AD they will be replaced with true cavalry helmets. Narrowly enclosing nearly the whole head, except the face, they will offer good protection against attacks from all sides in a prolonged cavalry melee. Their swords are either type Mainz gladii or Celtic longswords, ancestors of the spatha, the first real roman cavalry sword. Introduced around the midst of the 1st century AD the fine and well balanced spatha will become the main sword of the cavalry for the remaining centuries of the empire’s existence and even replace the gladius as primary infantry weapon in the late roman army. With its two-sided narrow blade the spatha is considerably longer than the gladius and much better suited for use from horseback. The use of the one handed hasta lance as primary weapon allows the horsemen to handle large shields with their left hand. The hasta’s compactness allows it to be used mainly overhand, to stab from above at the enemy besides rarer attacks in the conventional way and even to throw it in emergency situations. Like most of the imperial army’s cavalry, they use the famous four horned saddle, which enables a firm seat in almost all occasions.
The training of the alae is excellent and extensive, their equipment makes them multifunctional. They can weaken enemy formations with javelin showers and than attack with their lances in the very next moment. However, this versatility has its price. Their horsemen are comparably lighter armoured than the former Hellenistic cavalry or even the heavy cataphractarii of the east and the hasta is shorter than many of the cavalry lances used by our enemies. The alae should only be used with care against such opponents.
Historically, the large majority of the cavalry in roman service in the late republic were irregular auxiliaries of mostly Celtic or Iberian origin and their influence will remain dominant in roman cavalry warfare for the next centuries. Some of these units were already organized and commanded by Romans or served that long aside the legions that they had been largely Romanized in the mean time, while others were still commanded by their own leaders. In the early Principate they become a fully integrated part of the professional imperial army. Their training and equipment was unified and brought to a similar level of quality than in the legions they should cooperate with.
The alae (ala/ lat. wing) received their name for the cavalry's natural position in a battle formation, the flanks. These units had an excellent reputation in the imperial army and were ranked highest among the auxilia. Later it was not uncommon for exceptional horsemen from the legions to be transferred to an ala. Normally, one or later mostly two of them cooperated with each legion during campaigns and together they formed the core of the Principate’s armies. The 4th century military theorist Vegetius reported that only for ala and legionary first cohorts units a minimum height requirement of at best six (1,77m) or at least 5,5 roman feet (1,62m) had existed.
The standard ala quingenaria of the early Principate consisted of 16 turmae with 32 men and was armed as above. However after almost a century of warfare in the east some were already equipped as horse archers. Later in the second half of the 1st century AD elite ala millaria with 24, approximately 40 men strong, turmae will be formed and in the early 2nd century units of catafractarii and contarii will appear under the increasing influence of Parthians and Sarmatians on the development of roman cavalry. Most alae were named after the ethnicity of the original recruits and kept their name even if they were transferred to other parts of the empire where they immediately begun to recruit locals as replacement.
During the decades of his rule following the end of the civil war, Augustus reformed the imperial army significantly and created a standing army with 28 legions as its core. In many fields a systematic approach replaced the improvisation of the late republican era. Most important was that the auxilia, with its indispensable cavalry and archer units, became a regular arm of the professional army and its second base.
Their soldiers were equipped in the Roman fashion, and well commanded first by proven Centurions, transferred from the legions and later by a corps of equestrian officers. They were mostly recruited from amongst the peregrines, free provincials without roman citizenship, who either volunteered for service or accepted a draft into it. However, the transformation of the auxilia did not happen over night and the irregular contingents of soldiers supplied by allied tribes and vassal states did not disappear all at once. While the large majority of the cavalry units were reorganized during Augustus reign, the infantry followed much more slowly, lingering in the old fashions until the later years of the 1st century AD.
The length of service for all soldiers was finally set to 26 years for fleet soldiers, 25 years for soldiers of the auxilia, 20 years for legionnaires, and 16 years for praetorians. After their discharge they received a cash bonus, the praemia militare, or a small piece of land. The veterans from the auxilia and the fleet were rewarded with Roman citizenship, and a diploma to prove it. Also, medical treatment was improved and all units were now supplied with physicians.