Having lifted a siege of Florence, the Ostrogoths led by Totila turned on the pursuing Byzantines, defeating their numerically superior force.
Following his success against the Byzantines in the Battle of Faventia in spring 542, Totila sent part of his troops to attack Florence.
At their approach, the Goths raised the siege and retreated north, to the region of Mucellium (modern Mugello).
The Byzantines pursued them, with John and his troops leading the chase and the rest of the army following behind.
The Goths took many captives, who were treated well and even induced to join the Gothic army, while the Byzantine generals fled to isolated strongholds (Bessas to Spoleto, Justin back to Florence, Cyprian to Perugia and John to Rome), and henceforth failed to cooperate against the Goths.