Anyone who has ever seen the movie 'The Man in the Iron Mask' knows how creepy it is to look at an expressionless face. The Romans already knew that. Several face helmets were found near Nijmegen that Roman horsemen wore in battle. Modern techniques have been used to investigate how and what the helmets are made of. Behind the steel faces there are a lot of secrets.
The Roman Emperor Caligula began the construction of a series of castella . around AD 30 :Fortified camps to protect the northern border of the Roman Empire – the Limes – against attacks by Germanic tribes. The border of the Roman Empire ran right through the Netherlands. In the decades before the Batavian Revolt (69-70 AD), a Roman-Batavian cavalry unit was stationed on the Kops Plateau – a plateau in the east of Nijmegen.
In this video of reenactment group 'ALA!' you can see what such a Roman equestrian group looked like.
The Batavians – a West Germanic tribe that originally lived along the lower reaches of the Rhine – generally maintained good relations with the Romans. In the many battles against rebellious Germanic armies, their warriors often fought on the side of Rome. The Romans even built a permanent fortress for them:Oppidum Batavorum.
Numerous horse harness parts have been found on the Kops Plateau in Nijmegen. In addition, there is no known other fortification on Batavian territory where a cavalry unit was staying. Archaeologists therefore assume that this fortification east of Nijmegen was the home base of the Batavian cavalry. The whole area is a very rich archaeological site.
Pits
On the Kops Plateau, but also in other Batavian fortifications such as the Ulpia Noviomagnus Batavorum built after the Batavian Revolt. From which the later Nijmegen grew, some very special face helmets have been found among the countless metal military objects and other archaeological treasures from the Roman period.
These helmets are made of iron and were originally covered with a thin layer of silver. Face helmets like this have been used as battle helmets. The silver gleaming in the sun and the expressionless features were meant to confuse and terrify the adversary. It is probably a Batavian version of equestrian helmets that were also used elsewhere in the Roman Empire.
The masks were found in pits along with other military objects. The silver coating had been roughly removed. In ancient times, metal was precious and was rarely thrown away. Because jars filled with food and sacrificial animals have also been found in addition to the helmets, archaeologists suspect that the helmets were buried for a special purpose.
Probably – archaeologists differ on this – the soldiers donated their most valuable piece of equipment to the god who had protected them during the service by ritually burying these pieces. Sacrificing their military equipment would propitiate the god in question, so that he would again assist the soldiers on a next mission.
Experimental archaeology
Experimental archaeologists have tried to recreate the face masks. It turned out that the masks are made of a soft, low-carbon iron. Low-carbon iron is easy to deform and flexible, so it's less likely to shatter when struck during combat. Most masks consist of at least eight layers of folded iron. In order to get the iron mask as close as possible to the shape of the wearer's face, a deformable, organic underlayer was used, among other things, now also called floating pitch.
A Roman equestrian helmet consists of two parts. An iron helmet to cover the head and the forged iron mask in the shape of the wearer's face that was fastened to the helmet with straps.
The masks are made in such a way that they cover the entire face. The openings for the nose and mouth are large enough for good breathing. Traces of soft linen were found on the inside. This is for wearing comfort and to prevent sweat from oxidizing the iron.
The silver coating of all masks found in the vicinity of Nijmegen has already been removed in antiquity. However, a few traces that have been found are enough to establish that it was high-quality silver. The thin piece of silver must have weighed about 30 to 35 grams. A Roman soldier had to work 11 to 17 days for this. On the other hand, a soldier with a face mask was well protected:experiments with crossbows from Roman times showed that the masks were very resistant to the impact of heavy arrows.
Analysis of the helmet revealed geometric patterns of organic substances. The decorations consisted of a tightly braided pattern of linen and possibly colored human or horse hair. Clear traces of this have been found, but how the decorations were attached to the helmet is not entirely clear.
Tailoring the silver exactly turned out to be a difficult task. To avoid folds and dents, the silver could not be poured directly over the iron mask. Instead, it was made into just the right shape with the same moldable underlayment. An extra adhesive mass had to be used for firm fixing.
Antique adhesive strength
Traces of this adhesive mass were found between the iron substrate and the silver in a face mask that was found at Xanten in Germany. After analysis, this age-old glue turned out to consist of a liquid petroleum fraction, so-called bitumen. It also contained wood tar, which was probably obtained by burning pine trees.
The Romans managed to fine-tune the mixture for optimum adhesive strength and sufficient strength and toughness. The same glue may have been used to attach the decorations to the helmet.
All this attracted the attention of the German chemical group Henkel in 2007, which makes industrial adhesive applications, among other things. Henkel wanted to do further research to find out how the Romans managed to keep the silver and iron apart, despite having been in the soil for 2,000 years. Possibly the Roman ingenuity could lead to new glue applications. To date, however, no patent application has been made.