Battle of Mediolanum

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Coordinates: 45°28′00″N 9°10′00″E / 45.466667°N 9.166667°E / 45.466667; 9.166667

Battle of Mediolanum
Part of Roman-Alamanni conflict
and the Roman-Germanic wars
Gaius Messius Quintus Traianus Decius
Map of Roman Mediolanum
LocationMediolanum (modern Milan),  Italy
Result Roman victory
Permanent loss of parts of Agri Decumates
Roman Empire Alemanni
Commanders and leaders
Gallienus Unknown
60,000 armed 300,000 (warriors & civilians)
Casualties and losses
Unknown 300,000

The Battle of Mediolanum took place in 259, between the Alamannic Germans and the Roman legions under the command of Emperor Gallienus.


As Emperor Valerian, Gallienus´ father, was unable to be present in the battlefield, he named his son Gallienus Emperor. While Valerian was fighting against the Sassanid Empire and the Goths, who by that time had sacked Thrace and Asia Minor, Gallienus would be in charge of defending the Roman Empire's border.

In the Western half of the Empire, the situation was difficult. The Danubian border resisted continuous barbarian attacks. Gallienus had to march with military reinforcements from Gaul towards Dacia and Moesia to fight the Barbarians. The situation was so severe that in 259, the legions of Pannonia and Moesia rebelled and chose to make Ingenuus the emperor. Gallienus reunited the Rhine, left Legio II Parthica[citation needed] to defend it and went off to do battle.

Preliminary moves[edit]

Within the borders of the Rhine and the Alps, a Germanic confederation, the Alamanni, who occupied a good part of the Agri Decumates (the territory located between the mouth of the Rhine river and the Danube), crossed the Alpine steps and attacked the fertile plain of the Po river. The sacking of the area instilled terror in Rome, as it was still not a walled city. The Senate of Rome hastily prepared a crowd of plebs for combat[1] in an attempt to ensure that its shrinking army was capable of protecting the city. Gallienus had just defeated the pretender Ingenuus when the news arrived of the invasion by the Alamanni. He marched off with the legions I Adiutrix, II Italica and II Parthica[citation needed] to intercept the barbarians in Italy. By then, according to the Byzantine historian Joannes Zonaras, the Alamanni had retreated before the unexpected resistance of the citizens of Rome and its Senate.


When Gallienus arrived in the valley of the Po, he found the Alamanni in the vicinity of Mediolanum, present day Milan. The victory was total: according to Zonaras 300,000 Alamanni fell that day and the emperor received the title Germanicus Maximus.


The Alamanni's success in reaching into the Roman Empire once more revealed the weakness of the centuries-old tradition of posting Rome's legions near the borders without providing for defense within the empire. The battle of Mediolanum demonstrated to the Romans the value of swift, flexible military units. Afterward, Gallienus enacted a major reform by introducing a highly mobile field army composed mainly of cavalry (vexillationes). The main units were under the control of his General, Aureolus, and headquartered in Mediolanum, with the mission to protect Italy.

The Roman Senate had tried to regain its authority by arming and commanding its own military forces to meet the Germanic threat. But, uncomfortable with this challenge to his power, Emperor Gallienus suppressed all of the Senate's military prerogatives.[citation needed]

Finally, the invasion by the Alamanni demonstrated the vulnerability of Italy and especially Rome. This later caused Emperor Aurelian to have a strong wall built to defend the capital of the Empire.


  1. ^ "Emperor Gallienus". Retrieved 2008-01-14. 


  • Francesco Bertolini. Historia de Roma.
  • Michael Grant. Gli Imperatori Romani.
  • José M Roldán, José María Blázquez, Arcadio del Castillo. Historia de Roma, Tomo II El Imperio Romano.
  • José Manuel Roldán. Historia de Roma.
  • Historia Augusta.
  • Joannes Zonaras. Epitome Historiarum.