Skeletons in 1,700-year-old Croatian mass grave are Roman soldiers: study

Archaeologists have confirmed that skeletons discovered in a mass grave in the eastern Croatian city of Osijek belonged to Roman soldiers, shedding new light on one of the bloodiest battles of the Roman Empire's 3rd century crisis.

The remains of seven adult males were uncovered in 2011 during excavations at the site of the University Library. Unusually, the skeletons were found inside a repurposed water well, thrown in while still fully fleshed, suggesting they were hastily buried after death, a research paper published in PLOS says.

Radiocarbon dating of the bones places the burial between 232 and 375 CE. A Roman coin found in the well, minted in 251 CE under Emperor Hostilian, further confirms the timeframe. Researchers believe the soldiers were likely killed in the Battle of Mursa in 260 CE, part of the turbulent period known as the 'Crisis of the Third Century.'

Signs of soldiers and battle

Analysis of the skeletons showed all were adult males, four aged 18–35 and three aged 36–50. They were taller and more robust than the average male in the Roman province of Pannonia, meeting historical criteria for army recruits. Physical stress markers on their bones suggest long-term, intense activity typical of soldiers.

Several skeletons also showed signs of violent death. Perimortem injuries included puncture wounds, likely from arrows or spears, and sharp cuts from swords. Healed injuries on some skulls indicate prior combat experience. Researchers also found evidence of lung infections, suggesting these men suffered disease even as they went into battle.

Diverse origins reflect Roman army recruitment

Ancient DNA analysis revealed that the soldiers came from diverse genetic backgrounds, including Northern and Central Europe, Eastern Europe, and the Eastern Mediterranean. None were locally descended from earlier Croatian populations. This diversity matches historical records of the Roman army, which recruited soldiers from across the empire.

Why a mass grave in a well?

The unusual burial context—a water well rather than a formal cemetery—suggests the soldiers' deaths were sudden and violent. "The bodies were deposited rapidly, which points to a catastrophic event, most likely a battle," the research notes. The Battle of Mursa was part of Emperor Gallienus's campaign to defeat the usurper Ingenuus, a clash described in historical sources as especially brutal.

The 3rd century CE was a period of political instability and military crisis for Rome. Known as the 'Crisis of the Third Century,' it featured rapid changes of emperors, foreign invasions, and civil wars. Battles like Mursa resulted in high casualties and chaotic conditions, explaining the need for mass graves and the presence of soldiers from across the empire.

The discovery of these Roman soldiers provides a rare, direct look at the human cost of the empire's internal conflicts and highlights how the Roman army drew on men from a wide geographic area to meet its demands.