The clipeus, Roman round shield

The clipeus is an oval type of round shield used by the Romans from the 1st century BC. Unlike the rectangular scutum, which was curved, the clipeus had a flat shape. This type of shield was likely adopted from the Celts during Caesar's Gallic Wars (58-50 BC).

Writers from classical Antiquity seem to sometimes confuse the different types of round shields. It is possible that the terms were often used as synonyms for all round shields at the time. This contrasts with the classification used by modern historians. Today, a distinction is made between:

• Parma – a small round shield, which later mainly acquired a ceremonial function.

• Aspis (also known as hoplon) – the well-known round hoplite shield.

• Clipeus – an oval round shield that from the 1st century BC was mainly used by auxilia troops and became common throughout the Roman army from the late 3rd century.

During the Gallic Wars, Julius Caesar already employed Gallic and Germanic mercenaries. Emperor Augustus continued this tradition and developed the auxilia units from it. In this period, almost the entire Roman cavalry was replaced by auxilia troops, while the Romans, as before, only allowed citizen soldiers into the legions. This brought about significant changes in the composition of the army.

In the 1st century BC, the parma (the smaller type of round shield) fell out of use with the Republican cavalry. From that moment, this shield was used exclusively by special legionaries, such as standard bearers. The clipeus, on the other hand, was introduced during this period as a shield for both the cavalry and the auxilia infantry.

The clipeus remained in use, even after the scutum was phased out as an infantry shield at the end of the 2nd century. Five examples from the early 3rd century have been found in Syrian Dura-Europos. These shields vary in height between 107 and 118 cm and in width between 92 and 97 cm. They have a slight curvature and are made from glued poplar wooden planks, with edges reinforced with leather and rawhide. 

Of the relatively few preserved examples of shield covers, it appears that the clipeus in the early imperial period was quite large and heavy. A notable example is a blunt-oval shield from Doncaster (mid-1st century AD), which is 125 cm high, 64 cm wide at the widest point, 10 mm thick, and – according to a reconstruction – weighed about 9 kg. This made it almost as heavy and large as the oval infantry shields from the republic. 

Two leather shield covers (tegimenta) from Valkenburg, Netherlands (Z.H.) confirm the variation in shape and size. The largest cover, approximately 130 cm high and 65 cm wide, tapered slightly at the bottom and was made from large pieces of goatskin. The smaller, more rectangular variant was about 100 cm high and 53 cm wide. Because the edges of these covers were folded and tied together, the shields themselves were about 5 to 10% smaller - approximately 120 x 57 cm and 92 x 46 cm respectively. The larger form may have been intended for infantry, the smaller for cavalry. However, images show that many riders also used the larger shields. There were likely differences per unit, function, or rank, just as was the case with the infantry.

An important advantage of the large clipeus-shield was the protection: it covered the rider from chin to calf, and in some cases even offered partial protection to the horse. As described by Arrianus, riders could even form a sort of 'shield wall' with it that largely shielded them from arrows and projectiles. In hand-to-hand combat, the shield also provided a significant advantage for a skilled user, even against more agile opponents.

There is a persistent theory that cavalry shields had vertical handles, allowing the rider to hold the reins simultaneously. But many tombstones show postures that exclude such a handle. Moreover, holding the reins during a fight probably plays only a subordinate role: a rider actively using his shield cannot possibly maintain full control of the reins.

The construction of the clipeus was similar to that of the scutum. The shield consisted of vertically glued wooden planks, covered on both sides with painted leather or linen. The edges were reinforced with raw, sewn animal hide or with brass. The raw hide had a particular advantage: upon drying, it shrank the material, providing the shield with extra strength and cohesion. This reinforcement was also lighter than the brass edges used in other models.

Findings such as those in Dura-Europos and the Nydam bog indicate that the clipeus was generally larger than the scutum. While the scutum was medium 105 to 107 cm high, some recovered clipei measured up to 125 cm in height and 70 to 80 cm in width. Like the scutum, the center of the clipeus featured an opening for the handle, covered with a metal shield boss (shield boss) made of iron or bronze. Although it is difficult to determine from found parts exactly which type of shield belonged to which equipment, the shield boss's of the clipeus seem to more often have a round basic, whereas the scutum more frequently had square, rectangular, or hexagonal shield boss's.

Titus Livius (59 BC – 17 AD) describes in his magisterial historical work Ab Urbe Condita (“From the founding of the city”) the Roman history from its mythical foundation to his own time. In the early books – especially those on the royal and early republican period – he refers to the use of the clipeus as part of the standard armament of Roman soldiers. In books 1–3, which cover the wars under the kings and early consuls, Livius uses terms like clipeus to refer to the round shield that soldiers carried before the introduction of the more rectangular scutum. In this context, the clipeus often symbolizes an older, archaic form of warfare, and the shield is probably confused with the hoplite shield, the aspis.

Pliny the Elder (23–79 AD) discusses the clipeus in his encyclopedic work Naturalis Historia, especially in the context of art, metalworking, and votive objects. He was highly interested in how materials were used in visual art and religion. Book 34 – De metallis – discusses the use of bronze for art objects, including shields. 

Some clipei were adorned with reliefs of gods or heroes and could be very artistic and costly. Pliny mentions Greek artists such as Euphranor, who decorated clipei.

Pliny also describes the practice of painting a bust-portrait of an ancestor on a clipeus and hanging it in a temple or other public place. From this arose round reliefs in medallion form on sarcophagi and in other forms, known as imago clipeata or 'clipeus portraits' — a term usually confined to Roman art.

The clipeus virtutis, Latin for 'shield of bravery', was awarded to Augustus by the senate for his 'courage, clemency, justice, and piety' and was displayed in the Curia Julia.

The exterior of the clipeus was often painted with the unit's insignia – ornaments and symbols that allowed soldiers to distinguish themselves. This painting was usually only visible during battles or parades. Outside of these, a leather cover (tegimentum) protected the shield from moisture and damage. These covers, of which several have been found, were usually made of goatskin and were fastened with straps on the inside of the shield. Sometimes they contained openwork inscriptions in the form of a tabula ansata, which provided information about the carrier's unit.

Cavalrymen likely used carrying straps to bear the clipeus when it was not immediately needed. Unlike infantry shields, no complicated double suspension was necessary for this, as cavalrymen did not need to carry their sarcina (field equipment) on the clipeus. Still, it is doubtful whether they often hung the clipeus for long periods on a belt on the back or side. According to Flavius Josephus, Vespasian's cavalrymen preferred to attach their shields to the saddle during marches, so that they hung on the side of the horse.

Although carrying a clipeus somewhat limited arm movement, the rider could adapt depending on the situation. Simultaneously handling weapon, shield, and reins required a high degree of training – both from rider and horse. Under ideal conditions, a skilled rider could even control his horse largely without reins, something also described by Emperor Maurice in his Strategikon (book II, chapter 6).

The assumption by author Herbert Schwarz that Roman cavalrymen never actually wore shields and that all depictions of it are merely artistic license is contradicted by numerous ancient sources. Just consider the Tactica of Arrianus, in which the use of shields by the cavalry is described in detail.