The Battle of Mucellium was an engagement in 542 near Mugello, Italy, between Ostrogoths (Goths) and Byzantines during the Gothic War.
Byzantine forces advanced against the Goths, who had recently lifted the siege of Florence and camped in Mugello. Although the Byzantines outnumbered the Goths, Totila's forces routed the Byzantine detachment on a hillside, triggering panic that spread to the rest of the army leading to a complete collapse. The Goths captured prisoners, while the surviving Byzantine commanders fled to isolated strongholds. The lack of coordination by the remaining Byzantine forces allowed Totila to launch a successful campaign in southern Italy and eventually advance against Rome in 544.
View the full Wikipedia page for Battle of Mucellium