The short version is that at some time around 1200 BCE some sort of combat took place along the bank of the Tollense River on the north German plain.
The Tollense valley is glacial and about half a kilometer wide. At the time of the fight it was getting increasingly marshy as Holocene post-glacial sea level rise lifted the level of the Baltic and inundated the plain.
In Bronze Age times the streambed was broad, and flat, and probably studded with alder and birch.
The surrounding forests were dominated by oak, ash, lime, and elm. Jantzen et al (2010) says that "The Bronze Age environment can be described as a partly open landscape that showed limited human impact. However, flax, barley, oat and wheat pollen indicate some farming activities (nearby)".
We don't know who the combatants were who met in the Tollense valley in that year near 1200 BCE, or why they fought, of what the outcome was. The most common explanation is some sort of pitched battle between warbands:
"About 3200 years ago, two armies clashed at a river crossing near the Baltic Sea. (T)his was no skirmish between local clans. Thousands of warriors came together in a brutal struggle, perhaps fought on a single day, using weapons crafted from wood, flint, and bronze, a metal that was then the height of military technology.This is not the only explanation and, frankly, is hard to square with the presence of elderly and infant remains among the dead.
Struggling to find solid footing on the banks of the Tollense River, a narrow ribbon of water that flows through the marshes of northern Germany toward the Baltic Sea, the armies fought hand-to-hand, maiming and killing with war clubs, spears, swords, and knives. Bronze- and flint-tipped arrows were loosed at close range, piercing skulls and lodging deep into the bones of young men. Horses belonging to high-ranking warriors crumpled into the muck, fatally speared. Not everyone stood their ground in the melee: Some warriors broke and ran, and were struck down from behind.
When the fighting was through, hundreds lay dead, littering the swampy valley. Some bodies were stripped of their valuables and left bobbing in shallow ponds; others sank to the bottom, protected from plundering by a meter or two of water. Peat slowly settled over the bones. Within centuries, the entire battle was forgotten."
robbery on a massive scale as a raiding party bushwhacked a merchant party and its armed guards:
"A Silesian caravan transporting large quantities of tin and other metals was moving...along the Tollense river...protected by armed guard which consisted of both horsemen and infantrymen. The caravan was attacked by a gang or even a small...army which probably came from the north west, probably from the Jutland peninsula or even further north. These people were armed with more primitive weapons, arrows with flint arrowheads, wooden spears and wooden clubs. Denmark and Sweden have huge flint deposits so it is quite possible that the attackers came from there.
The attackers...launched a surprise attack from the forest which surrounded the river. They first pelted the caravan with arrows, targeting the mounted soldiers first. This is why we have dead people mixed with dead horses. Remember the clustered bronze arrowheads mixed with human and horse bones? Were they the arrows which the horsemen never got to take out of their quivers? I believe that the arrows with the bronze arrowheads were fired by mounted archers. The proof for that is the bronze arrowhead which was found embedded in a skull. This arrowhead could only have been fired from a position above the head, which would indicate that the archer was on a horseback.
Also the flint arrowhead which was found embedded in a humerus (upper arm) bone is embedded under such angle that the shot must have come from below, meaning that the arrow was fired by a foot soldier shooting a mounted warrior.This interpretation is in the minority. The bulk of the scholarship gleaned from the Tollense concludes that this was the clash of arms; feuding tribes, or even more - the assembled warbands of a local king, perhaps, or remnant of a mass migration produced by the stress of changing climate. The women and children? Camp-followers; Bronze Age logistical support elements.
(After the exchange of bowfire) the frontal assault ensued which resulted in hand to hand battle. It is most probable that the attackers won. The number of dead would suggest that this is what happened. The attackers killed all the people from the caravan, collected all the metal, metal armor and weapons and other valuables and remaining pack animals and returned back to wherever they came from. They left all the dead Silesians where they fell."
"The number of individuals (~100) so far identified from the Tollense Valley, who were probably killed during a conflict over some days or weeks, is on a larger scale than earlier examples for potential violence (see Thrane 2006: 278). It is unclear whether we are dealing with professional warriors. Some women and children are also present in the sample; according to ethnographic data they could have supported the men in fighting, for example by organising food or by carrying weapons (Keeley 1996: 35). The considerable number of individuals involved does not support the scenario of a small-scale conflict of local farmers or small war bands (Osgood 2006). Some bronze pins of Silesian types (Ulrich 2008) found in the Tollense Valley indicate close contacts with this region (~400km) to the south-east. First results of δ13C and 15N analysis of the human remains indicate millet to be part of the diet, which is uncommon during the Early Bronze Age in northern Germany, and might suggest invaders from the south."Or the the travelers were from the south and the invaders were from the north...how could one tell from the bare bones and metal and stone? The answer is that we can't.
Which, in its way, is a good reminder. That for all that we think of "history" as the great events, the memorable and the remembered, history is made up largely of people like you and me, living ordinary lives and dying ordinary deaths and being forgotten, leaving nothing behind us but our bones.