Roman military accounts from the early centuries CE describe the tribes of north-central Europe as fierce fighters who took the field with large forces and treated vanquished foes with ritual brutality. Until recently, however, there hasn’t been much archaeological evidence to back up the Roman accounts. But some time in the first century CE, two of those tribes clashed in what is now the Alken Enge wetlands in the Illerup River Valley in Denmark. Archaeologists excavated the aftermath from 2009 to 2014, finding broken weapons and shields along with the bones of at least 82 men.

Many of the bones bore the marks of grievous wounds dealt just before death, which is no surprise on a battlefield, of course. But all of them were found in places that would have been under water 2,000 years ago—and they’d all been left exposed to weather and scavengers for six months to a year before they ended up in the water.

Archaeologist Mads Kähler Holst of Aarhus University in Denmark and his colleagues say it’s the earliest example so far of a practice common in northern Europe in the first few centuries CE. In lakes and peat bogs all over northern Europe, archaeologists have found sites where people deposited the broken weapons and shields of their defeated enemies in the water. Most of those so-called “weapons graves” date to the second through fifth centuries CE, while the bones at Alken Enge radiocarbon dated to between 2 BCE and 54 CE.

And Alken Enge stands out from later sites, which consisted mostly of broken weapons and shields tossed into lakes and peat bogs, with very few human bones. That led some archaeologists to speculate that these Germanic tribal conflicts didn’t produce many casualties, perhaps because the battle focused on taking out tribal leaders or because the victors wanted to take their defeated enemies as slaves, not kill them. But Alken Enge offers some of the first evidence that the brutal military conflicts the Romans wrote about really did happen, with large numbers of people involved and lots of casualties.

Unknown combatants

Based on radiocarbon dating of the bones (mostly collagen from lower jaws), the battle at Alken Enge happened at around the time the Roman Empire was expanding into what was then northern Germania. It’s possible that the pressure of Roman expansion sparked, or at least intensified, conflicts among the local tribes.

But archaeologists aren’t sure exactly who fought here, let alone who won or lost the battle. There’s no indication of tribal affiliation on any of the weapon fragments found so far, and personal equipment like belt fittings and dress pins that might reveal more about the status and identity of the dead are conspicuously absent.

But the broken weapons found in the wetland—spearheads, fragments of swords and shields, an axe, and some iron knives—are all clearly Germanic. The metal they were made of came from the local Jutland area, according to metallurgical analysis on some of the weapons. And the patterns of injury on the bones speak of lances, swords, and perhaps axes.

“High incidences of perimortem trauma show that the conflicts were extremely destructive in character, with consequently comprehensive slaughter,” wrote Holst and his colleagues. The nature and scale of the carnage recorded in the bones at Alken Enge lends concrete support to the Roman historians’ descriptions of their own troops’ violent encounters with the northern European tribes.

Large-scale battle

The 2,095 human bones excavated at Alken Enge represented at least 82 people; left femurs were the most common single bone at the site, and archaeologists found 82 of them. But there are probably at least 380 individuals’ remains somewhere beneath the 75 hectares of wetland at Alken Enge, mostly in areas that would have been underwater in the first century CE. But the battlefield—and the likely spread of human remains—stretches farther to the north and east than archaeologists were able to excavate.

“Test pits and previous finds of human remains demonstrate that the find concentration extended further to the north on the eastern side of the sand spits but modern settlement complicates an investigation of this area,” the archaeologists wrote (a cheery thought for the area’s modern residents).

That many people probably didn’t come from a single village, because archaeologists have never excavated an Iron Age village in the region that could have supported anything close to that number of people. Instead, the force was probably recruited from a wider area. And those recruits were probably green troops; very few of the bones showed signs of old, healed injuries of the kinds that would indicate wounds from previous battles. Most seem to have been young men, between 20 and 40 years old.

“Alken Enge confirms the indications in the historical sources of early, large-scale military capabilities in Northern Germania,” wrote Holst and his colleagues.

Ritual disarticulation

After the battle, the defeated were left on the battlefield for six months to a year. Many of the bones show tooth marks and cracks, signs of being gnawed by smaller scavengers like foxes, wolves, and dogs, and a few have spiral fractures from being cracked open by larger scavengers hoping to get at the marrow inside. That’s not so unusual.

But then someone came back, months or a year later, to pick the bones up and put them in the lake.

At the time, the area was a rough meadow, dotted with wooded groves surrounding the shores of a shallow lake. A pair of sand-spits extended out into the lake, and most of the human remains at the site were found in what was once the deepest part of the channel between them, as if people had stood on the sand-spits and thrown the remains into the sheltered waters.

It seems to have been a ritual of some significance, not just a cleanup effort. Some of the bones showed the kinds of cut marks usually associated with butchering, which means someone went to the effort of separating the few bones that still had ligaments holding them together after several months of decay and scavengers. (There were a few exceptions, including the legs and some foot bones from one person, and a lower leg and some foot bones from another.)

And although most of the disarticulated bones were scattered seemingly at random in the water, a few sets were treated differently. Archaeologists found four hip bones stacked together with an alder branch running through the obdurator foramen (the large opening in the hip bone for blood vessels and nerves to pass through) of each bone. And on the slopes of one of the sand spits, a femur, fibula, and tibia (the bones of the leg) were found bundled together with two white stones. The bones came from at least two different individuals, and the white stones were of a type that doesn’t occur in the Illerup Valley, so they must have been imported somehow. We can only guess at the reason.

It’s not clear whether the battlefield was adjacent to the lake or whether the people who deposited the disarticulated remains of their enemies at Alken Enge carried them there from somewhere else. At another martial burial site in southern Denmark, materials were carried more than a mile from the coastal battlefield to an inland bog for ritual disposal.

In the layers of sediment above and below the human remains, archaeologists found an assortment of animal bones, pottery, and even parts of wagons, which indicates that people had used this landscape for centuries before the battle and continued to use it for centuries afterward.

“There appears to have been periodic ritual activities at the location, not unlike other martial sites,” wrote Holst and his colleagues. There are several other ritual lake deposits of weapons from the 3rd to 5th centuries CE elsewhere in the Illerup Valley.

PNAS, 2018. DOI: 10.1073/pnas.1721372115 (About DOIs).