Under the Emperor Justinian, a Byzantine Army under the General Narses was provided the earlier lacking funding, and the army marched to recover Italy for the Empire. Narses’ army was a combination of Roman regulars , and the elites of he tribes of Germany, Lombards, and Heruls. Narses proceeded into Italy along the well-known invasion route from the Northeast. Narses’ engineers demonstrated their skills at siege tactics and field engineering by the construction of bridges across the mouths of rivers and the relieving of the garrison at Ravenna.
The Italian-Gothic King Totila attempted to stop Narses with a massive charge of his cavalry on the Via Flaminia (near Ravenna) and was defeated. At this point the Goths invited the Franks to enter the contest and take Italy for themselves. King Theudebald of the Franks dispatched two dukes; Lothar and Butilin to undertake this task.
Early in 554 the Frankish dukes divided their army, went around Ravenna, and moved South, down the peninsula, taking booty and prisoners as they moved. In the early Autumn Butilin moved toward Rome. He was on the trail of Narses, whom he needed to bring to battle. His army was suffering from dysentary and a victory was needed while he still had the force to make it happen. He arrived in Compania along the North bank of the River Casilinus (River Volturno) and constructed a fortified camp with earthworks and a bridge across the river guarded by a tower. It was at this point that Narses arrived on the scene. The Byzantine drove in the German foragers, burnt the tower, and captured the bridge. Butilin was now faced with the inability to forage for food and thus was forced into a battle with the Byzantines.
Narses set out with a defensive blocking force of infantry and dismounted cavalry. In the center were the “antesignani” (1) and on their flanks the other heavy infantry. Behind the infantry were slingers and bowmen, ready to fire over head into the advancing enemy, and a body posted as rear guard. If Narses followed the same practice as at Taginae (battle) the rearguard was composed of cavalry, and not (as depicted in some reconstructions) an infantry line. The Herul troops were in dispute with their general at the time, one of their number having murdered a servant and been executed by Narses order. The Heruls were near mutinous, but were calmed by Sindual, their leader, and were marching up to fill a gap left for them, possibly behind the “antesignani.”
Narse arrayed his cavalry on both flanks. He took post at the tip of the right wing. This was probably to control it and perhaps to take advantage of the good view provided by the rising ground. On the lft flank he concealed the cavalry in a wood with orders to emerge only when the enemy was in contact with the center. The plan was to hold the German charge and then turn the flanks with cavalry.
Butilin formed his men into a line with a “Boar’s Head” (wedge) formation in the center, with unit echeloning back either side. The whole formation was like an inverted “V” with the strike force at the head. The Alamans charged yelling their battle-cry as they advanced. The byzantines braced themselves while shooting their bows and slings at the onrushing wall of shields. When the Germans crashed into the Byzantine line shield battered against shield, the din would have been terrific. In the center where the Heruls should have been, the Byzantine infantry broke under the force of the German “Boar’s Head” charge, the dense wedge pushing past the rearguard headed towards the advancing Heruls.
Narses then advanced the Roman Cavalry on both wings so they could shoot their bows at the unprotected rear of the Germans on their flanks. While the Roman infantry held back the bulk of the German army, the Heruls counter-charged the wedge, which had attempted to turn and take the Byzantines in the rear. Butilin was surprised by this fresh force, because previous intelligence from Herul deserters had suggested that their tribe would not fight. The wedge broke, as the Heruls forced their way into the gap left for them in the line. Narses then released his cavalry to sweep around the wings and take the german force in the rear. This disposed of the wings that were still fighting. Surrounded, the invaders were massacred, with only a handful making it back to their homes cross the Alps.
“antesignani” -- heavy armed foot, wearing cavalry armor of long mail coats, and some with spear, javelins, and long spiked shield;
Matthew Bennett, et al, “Fighting Techniques of the Medieval World, AD 500 - AD 1500, Equipment, Combat Skills, and Tactics,” Amber Books Ltd., New York, 2005, pges 12-13, (ISBN 0-312-34820-0)