Although Roman legions were formidably strong, they were best suited to fighting enemies on foot; against horsemen wielding swords, they could gather in a defensive formation and break the attack using gladius and pilum once the enemy had approached enough, but archers on a horse represented a dangerous issue for the legionaries.
An example of such disadvantage is represented by the defeat at the hand of the Parthians in the 1st century BCE: thanks to their superior mobility, it was easy for them to drive off the auxiliary cavalry and defeat the legions from a distance. The battle of Carrhae in 53 BCE showed that even the Roman army had a weakness, giving the chance to other tribes that made predominant use of mounted soldiers – such as the Huns – to raise and increase their incursions against the Roman Empire.

Initially, legions included only 300 cavalry, mainly from the wealthier class of the Roman society, but soon that number was doubled. The early legions acquired mobility, but the main and stronger attack still relied on the much larger part of the army formed by the infantry. This became the only component of the legion when the cavalry was removed from the formation and included instead in the auxiliary troops. This meant keeping the cavalry as a secondary element, despite their increased number, and using it mostly for scouting or as flank guards.

In time, the army adopted a more defensive mindset and static strategy, and the cavalry was assigned the duty to patrol the borders of the Empire between the various fortified settlements and to face the incursions and small revolts of the tribes living just beyond those borders.
During this period, the Roman army had no unified equipment, which could vary from unit to unit, but the cavalry was usually armed with light throwing spears and a sword. Even though Roman legions are known for their use of the gladius hispaniensis, which derived from the “Spanish” sword used by the Celtiberians, their first weapon was a heavier Greek-inspired sword; as the army evolved, both were abandoned in favour of a longer blade, the spatha, ideal for cutting strokes and more similar to the “barbarian” swords. Over time, towards the late period of the Roman Empire, legions were mostly armed with the tribal weapons adopted by the individual soldiers. Some cavalry were equipped with lances instead of throwing spears, and most of them wore light protections such as scale or mail coats, helmets and shields – much heavier armour was adopted by the troops of the Eastern Roman Empire.

As it became clear that the cavalry had to be a more predominant force within the army, the number of mounted soldiers increased and their role changed. Moreover, more “barbarian” people, rather than the civilized Romans of the provinces, were often employed into the cavalry, replacing the infantry as the main formation.
By the time of the fall of the Western Roman Empire, the prowess and importance of the cavalry had grown to the point that being a mounted soldier meant, inevitably, belonging to the upper class, as the costs of maintaining a horse and the entire military equipment could only be met by the wealthiest members of society.

Since the late days of Rome, such correlation between high social status and being part of the cavalry – or a “knight”, as in later times these soldiers came to be called – has represented one of the most important factors of the political and military affairs of the European history.

*featured image: Roman cavalry fights the Frankish army, Rava, Giuseppe (b.1963) / Photo © Rava / Bridgeman Images