The oldest deposit alone held about 300 spear points, along with shields, belts and scabbards, some 129 tinderboxes and 124 combs. Combs and tinderboxes are the details that make it concrete: this was not a symbolic scattering of a few blades but the stripped possessions of men who had been carrying everything they needed to live in the field. Weapons make up the bulk of the assemblage, but personal equipment runs through it, and the deposits fall into several episodes across the site's use, associated with roughly 200, 225, 375 and 450 AD. Each episode represents a separate defeat. The valley absorbed the losers of one war after another for two and a half centuries.

Among the spear points, two carry the name Wagnijo in runes — Elder Futhark, from the earliest period of runic writing in Scandinavia, when the alphabet was young and its use rare. A silver shield grip found at the site bears another inscription, NITHIJO TAWIDE. These are among the oldest written words to survive from Denmark, and what they preserve are not laws or prayers but names attached to weapons. Whether Wagnijo was a warrior, a workshop or an owner is not settled. The inscriptions do establish something else: the men who fought here belonged to a world that had begun, in a small way, to write itself down.

The consensus is that the material is captured enemy equipment. Victors gathered what the defeated had carried, destroyed it, and gave it to the water as a votive offering. The destruction was not incidental damage from combat; it was done afterwards, deliberately, and it removed every practical use the objects had. That behaviour is not unique to this valley. Illerup Ådal is one of about twenty-five weapon-sacrifice sites known across Denmark and southern Sweden, spread through eastern Jutland, Funen, Lolland, Zealand and Bornholm, and across the water on Öland and in Västergötland. The armies whose gear ended up in Illerup appear to have come from around the Baltic, mostly from other parts of Scandinavia — which makes these the remains of northerners fighting northerners, several times over, with the winners handing the spoils to their gods rather than keeping them.

The lower end of the valley is Alken Enge, a stretch of wet meadow near Lake Mossø, and it holds something harder to look at. In 2008 and 2009, during a large excavation carried out with students from Aarhus University, the skeletal remains of hundreds of Iron Age people were found across a site of about 40 hectares, in what was probably a lake bed when the bones were placed there some two thousand years ago. Most are thought to be warriors, and some may have been prisoners killed after the fighting. The Alken Enge dead predate the Illerup weapon deposits. Mads Kähler Holst, the archaeology professor from Aarhus University who managed the excavation, put it plainly: this must have been a far-reaching and dramatic event, one that had a profound effect on the society of the time.

Much of Illerup Ådal has never been dug. The valley was given protected status in 1996 precisely because it still holds material, and the decision was to leave it where it lies rather than exhaust the site with the methods currently available. What has been lifted is on display at Moesgaard Museum outside Aarhus, where thousands of items from the valley form one of the great collections of Iron Age warfare anywhere. Standing in front of them, the scale registers differently than the number does. Fifteen thousand objects is an abstraction. Row upon row of bent spearheads is an army.