Transformations of a Helmet and a Rebellion
The oldest Roman helmet, in use already during the wars against Hannibal, is the Montefortino type. It was influenced by Celtic helmets. The Montefortino is a simple design of conical or round shape, made if iron or copper alloy (bronze, brass), sometimes tinned or silvered. The crest knob was usually made in one piece with the skull and would hold a horse tail crista (more like Éomer in the LOTR movies, not the red crest that Hollywood uses no matter which period of Roman history). The short neckguard is also made in one piece, but the cheeck pieces were added separately and often made of (boiled) leather, which is the reason they are rarely found. There are also rings or studs for the chin straps.

Earlier Monterfortino helmets were decorated with rope and pinecone patterns, but after Marius' reform of the army, when men who could not afford to buy their own gear could join, the helmet became a plain, mass fabricated standard issue.

Hagenau type helmet; Haltern
Halfway during the 1st century BC, another type of helmet appeared, the Hagenau (German teminology) or Coolus. And that's where things start to get complicated. For one, the English classification of helmets, introduced by Russel Robinson in the 1970ies, has never been adapted by German archaeologists and I admit I don't know it well enough to use it (I'll stick to the German distinctions), and second, several types of helmets were used side by side because older Montefortino helmets would not be thrown away just because an improved version appeared.

The Hagenau type helmet was of globular or hemispherical shape and added a brow reinforce, a ridge along the front of the helmet. The additional ridge may be due to the fact that the Romans had to deal with enemies who used longer swords for hewing (the Roman gladius was more a stabbing weapon), and in case of the Germans also battle axes and cudgels that could make a dent even in a Roman helmet.

The metal was 1.5 - 2 mm thick, and there was a lining of linen cloth filled with horse hair or sometimes felt at the inside of the helmet. The whole thing would weigh about 2 kg. The crest knob was riveted on; in some cases there were feather tubes at the temples - at that time, the crests came in use. During the march, helmets were worn attached to straps on the body armour.

Weisenau helmet; Haltern
The next type that appears is the Weisenau helmet (Imperial Gallic G), named after its first find near Mainz. The Weisenau helmet comes in a number of variants (and sub-groups on Robinson's list). It is worked more elaborately than the Hagenau/Coolus type, and Marcus Junkelmann suggests that it may have started out as a version worn by officers. It slowly replaced the older models during Claudian times and was used by the rank and file soldiers as well. The helmet is somewhat heavier than the Hagenau: about 2.3 kg.

Though the various helmet types still coexisted during the 1st century; the Weisenau became more common. It's the one you can find a lot in German museums at the Rhine. It's also the helmet most popular with reencactors of early Imperial armies - well, it looks cooler than the Montefortino, for sure. :)

Weisenau helmet with decorations; Worms
The Weisenau was always hammered into shape which makes for a better fitting while the older models often were spun on a lathe. The neck guard becomes larger and slighly slanted downward, there is always a brow reinforce ridge, the cheek pieces are made of metal and better adapted to the shape of the head, and the helmets are decorated with etched patterns, stamped bosses and applied brass features, often tinned or silvered. Some models have a carrying handle. There are rings for chin straps at the rim, and the cheek pieces were secured under the chin as well.

The Weisenau started out as infantry helmet but soon was used by the cavalry as well, albeit often with a somewhat shorter neckguard in which case it's also called a Weiler helmet. Weiler type helmets could be very elaborately decorated (see below).

Helmets are found without cheek pieces in most cases though one can't say for sure if the lost parts necessarily were made of perishable material; there are reasons why metal cheekguards - usually attached to the helmet by leather straps or hinges - may have disappeared.

Roman helmet (Weisenau type?); Xanten
There's not always a type identification of a helmet in a museum display beyond the approximate date (calibrated according to the place of the find and the layer of dateable material like coins), and the distinction between they various types lies often in details not immediately visible - or lost during the centuries in the earth. The one above looks like a Weisenau helmet to me because of the long neckguard, but it lacks decorations (and cheek pieces). But the shape is very elegant which caught my eye.

Now look at this beauty, and the others above. Why on earth would someone change such a helmet into this?

This is a reconstruction modeled after a find at Krefeld-Gellep (Gelduba) and today shown in the Museum Burg Linn. The helmet, of Roman craftmanship, showed traces of fur and feathers. A member of the reenactment group Classis Augusta Germanica I met in the Archaeological Park Xanten had that helmet on display outside his tent. The rest of the group, featuring auxiliaries of Germanic origins, had adapted Roman military gear, tools, clothes and all, but this guy kept to his barbarian ways. *grin*

The 'improved' helmet was found in a place that connects it with the Batavian rebellion. The Batavians were a Germanic tribe that separated from the Chatti in 38 BC; and Augustus' general Agrippa allowed them to settle west of the Lower Rhine, on the Roman side, in what is now part of the Netherlands (the Rhine delta and Betouwe insula).

The Batavians were exempt from paying tributes and taxes in exchange for military service as infantry and cavalry soldiers. They were brave warriors and moreover, able to swim rivers in full armour and with their horses without breaking formation - the Batavian Mounted Amphibian Corps. *grin* Batavians formed the Emperor's personal guard in Rome, Batavian contingents fought at the side of Germanicus against Arminius (their chief Chariovalda fell at Idistaviso in AD 16), accompagined Claudius to Britain (battle at the river Medway AD 43), fought at Mons Graupius AD 83, and were stationed at the Hadrian's Wall and at the Danube. They soon became regular auxiliaries led by their own nobles who received the Roman citizenship.

(Batavian auxiliary soldier with Gallic Imperial A (Nijmegen) helmet, spatha, and shield boss; Xanten)

One of those leaders was Julius Civilis. He had partaken in the conquest of Britain where he may have met the future emperor Vespasian who served as legate of the II Adiutrix. But in AD 68, Civilis was arrested for treason (he may have been involved in Vindex' ill-fated insurrection, but we don't know for sure) and sent to Rome in chains; his brother was executed. Here's the short version of how things got downhill from there:

Nero committed suicide (AD 69) and his successor Galba, a friend of Vindex, acquitted Civlis and sent him home. Galba also disbanded his Batavian bodyguard, an act that offended them greatly. Back at the Rhine, Civilis was arrested again, this time by the governor Aulus Vitellius. Galba meanwhile was assassinated by the Praetorian Guards in Rome (he should have kept that Batavian bodyguard), and Otho took over. At that point it became clear that the job of emperor was open for grab. Vitellius released Civilis and marched to Italy to fight Otho, eight Batavian cohorts in tow. He won the battle of Bedriacum; Otho committed suicide. The Batavians were sent back to Moguntiacum (Mainz).

But meanwhile in the east, Vespasian had been hailed Emperor by the legions he commanded. AD 69 is called the Year of the Four Emperors, and there were still two left to fight a nice little civil war.

Vitellius needed more troops and pushed the conscriptions among the Batavians too far. The Batavian units stationed at the Lower Rhine, led by Civilis, revolted. They won over the Cananefates as allies and conquered several Roman forts on Batavian territory, most of which where undergarrisoned. The Batavian cohorts in Moguntiacum fought their way through the Romans to reach Civilis.

Vitellius next dispatched two legions - the V Alaudae and the XV Primigenia - and more auxiliary troops against Civilis, but the battle near Nijmegen ended in a disaster. The auxiliaries either switched sides (the Batavian horse led by one of Civilis' personal enemies, and a cohort of Tungrians) or fled, and the legions were forced to retreat to Castra Vetera (Xanten). Vespasian sent Civilis a letter that he didn't mind him keeping some of Vitellius' forces busy at the Rhine. *grin* Civilis himself dyed his hair red and swore he'd grow his beard until his lands were free from Romans. Says Tacitus. Civilis' motives are not known - revenge for his brother, personal ambition (he came from and ancient noble family, after all) ... we can only guess.

Display of the Batavian helmet
Maybe that's the moment our Batavian friend decided he wanted a more Germanic looking helmet. He took off the cheek pieces and neckguard, as well as the brow reinforce. Then he trimmed the rim with leather and glued a weasel or marten fur and some feathers to the remaining skull. Some Germanic helmets with fur decorations dating to the early Middle Ages have been found, but the Gelduba helmet is a rare example of an early German one.

Civilis laid siege to Castra Vetera where the two legions had fled. He could not take the place by storm, but he tried to starve them out. The troops stationed in Moguntiacum and Bonna (Bonn) were too few to lift the siege. By that act he went beyond anything Vespasian could have tolerated in an auxiliary officer supporting his claim.

And now the Gallic tribes of the Treveri and Lingones under the leadership of Julus Sabinus who claimed to be a great-grandson of Caesar, rebelled as well. Two legions (I Germanica, XVI Gallica) joined Sabinus and his 'Gallic Empire' in Trier.

Germanic tribes east of the Rhine joined Civilis, among them the Bructeri (who'd once been members of Arminius' coalition). The starving legions in Castra Vetera surrendered and were allowed to leave, but things got out of hand and they were massacred on the march, the fort put to fire.

(Decorated cavalry helmet type Weiler; Xanten)

There was a lot of marches back and forth, skirmishes between the Romans and Batavians, Romans and Gauls, the assassination of an officer, and other fun. I spare you the details; it's all very complicated and Tacitus' account not always clear.

Vespasian had won the war against Vitellius and could now put the provinces of Gallia Belgica and Germania Inferior back to order. He sent Quintus Petilius Cerialis with five legions and vexillationes of two more to put out the flames. They first dealt with the Treveri and Lingones, and Cerialis made them return to the Empire. Julius Sabinus was brought to Rome and executed. Civilis' Batavians had come to the aid of the Gauls at the battle of Trier despite their different goals, but could not defeat the Romans.

Civilis and his troops retreated to the insula between Rhine and Waal and cut a dyke to flood more land. The last battle between the Batavian rebels and the Romans took place in knee deep water, but the Batavians lost nevertheless. Civilis met with Cerialis to negotiate surrender. The Batavians were received back in grace and continued to provide auxiliary troops. We don't know what happened to Civilis, though, because the manuscript of Tacitus' Histories, the main source for the Batavian revolt, breaks off here.

The destroyed fort of Castra Vetera I was abandoned and a new one built closer to the Rhine. Due to the river changing its course, it is today buried under water and sediments. But the civilian settlement near the fort would become a Roman town - Colonia Ulpia Traiana / Xanten. Finds from the battles during the Batavian rebellion are displayed in the new museum in the Archaeological Park.

Face mask; Haltern
Among them is the beautifully decorated Weiler type parade helmet to the left above. Patterns of stylised hair were only one form of decoration; there are some rare examples of helmets that used braids of real hair. They may have been more common than the amount of finds suggest because real hair usually decomposes.

The cavalry in particular used to wear such decorated helmets on parades. They were not used for battle, though. The parade helmets could be worn with face masks like the one found at Kalkriese. That's not the only find, though, there's one in the LWL Museum in Haltern as well, and as in Kalkriese, the silver foil is missing. I was surprised how small those masks are.

There are discussions whether the masks were worn during battle as additional protection. I've been wearing a Weisenau helmet with cheek pieces and from my experience, a face mask would limit the vision too much - the cheek pieces already can get in the way a bit. Cheek guards and the brow reinforce ridges should keep off most blows, moreover the rim of the helmet goes down to the eyebrows. The only bit in some danger may be the nose.

2nd century Weisenau helmet with crossbars; Saalburg
The final step in the development of the Weisenau helmet was the addition of an iron cross ridge on the skull. This was invented in the early 2nd century during the Dacian wars. The Dacians lived in the Pannonian Basin and the Carpathian mountains north of the Danube (modern Romania and parts of Hungaria) and kept causing trouble. Emperor Traian had to fight several wars against them and in the end made Dacia a Roman province. The Dacians used the falx, a two handed pole-arm sword that consisted of a three foot long wooden pole with a curved iron blade of another three feet attached. The cross ridges on Roman helmets, often welded or riveted to helmets already in use with no regard to existing embossements, were a reaction to the damage those swords could cause.


Sources:
Frank Ausbüttel, Germanische Herrscher von Arminius bis Theoderich. Darmstadt 2007
Brone Bleckmann, Die Germanen. München 2009
Marcus Junkelmann, Die Legionen des Augustus – Der römische Soldat im archäologischen Experiment. Mainz 2003
Marcus Junkelmann, Die Reiter Roms, Teil III. Mainz 1992  ¶ January 17, 2011