For a fat, small-town equestrian with a civilian career behind him, Simplicinius Genialis was turning out to be something of a general. Some four years before he had defeated a force of Iuthungi and Semnones returning from the great Alamannic raid into Italy. Now he had selected an excellent defensive position for an army vastly outnumbered in cavalry. The road ran uphill through a highland plain about a thousand paces wide. Steep, heavily wooded slopes reared up on either side. These precluded not just cavalry but the movement of any formed body of troops. There was a small stream running along the tree line under the western escarpment, but Gallienus thought it was likely to prove of little consequence.
Simplicinius Genialis’s dispositions showed equal skill. He had drawn up his heavy infantry, six deep, in close order across the plain, filling it from slope to slope. Legio III Italia Concors, about four thousand men under the Spaniard Bonosus, held the centre. On their right were vexillationes from two legions from Germania Superior, VIII Augusta and XXII Primigenia, amounting to about a thousand shields. The left consisted of something less than a thousand Germanic warriors. They were on foot, but handlers held their horses a little way to their rear. Gallienus’s frumentarii had informed him recently that Postumus had despatched these Angles to Simplicinius Genialis.
Close behind the main battle line stood the provincial militia. Their numbers were harder to judge; by their very nature, they were ad hoc units. They looked to almost equal the total of those in the front. Raetia was a beleaguered frontier province, and its levies would have more experience of fighting than most. They had been a part of the recent victory over the barbarians. But militia could never stand up to regular troops in close combat. It had to be assumed they had been stationed there to hurl missiles over those in front. Should they want to, the amateur soldiers of Raetia would find it difficult to run. Some twenty paces to their rear were posted what Gallienus already knew were all the two thousand regular auxiliary archers in the province. Most likely, apart from shooting at the oncoming enemy, the latter also would have been given orders to shoot any of the militia who turned tail.
No reserve was to be seen, except, much higher up the road and thus well to the rear, almost back with the baggage, two alae of cavalry. At a distant glance it was evident that these were far less than the thousand riders which should have been on their muster rolls. Judging by the mounted messengers coming and going, Simplicinius Genialis himself probably was with them.
The array was completed by some regular auxiliaries on the extreme flanks armed with javelins and swords. Some of them could be seen now and then precariously scrambling between the trees on the vertiginous slopes. Given the terrain, despite the words he had spoken to the Cantabrians on his right, Gallienus considered it most improbable that troops there would have any influence on the outcome.
The emperor had had plenty of time to study his opponent’s order of battle. Simplicinius Genialis had chosen his ground well and set out his forces with acumen. Yet he had surrendered all initiative. For the past two days the imperial field army had watched the rebel forces. Each morning the army of Raetia formed up in good order, and each night posted adequate numbers of advanced pickets. The latter had little effect on the deserters. In the dark, men crossed from one side to the other, as was the way in any civil war.
Both days, the imperial army had remained in camp. They could not stay where they were indefinitely, because their supply line was too long and tenuous. They could not retreat, because that might prove fatal to imperial prestige. The troops were restless. Despite the advantageous position of their enemy, despite the terrible casualties that would come from plunging missiles, they were eager to advance. In part to curb this impatience, on the first day Gallienus had made it known he had sent two columns on flank marches to come around behind the enemy. One thousand Dalmatian horsemen under the Egyptian Theodotus had retraced their steps through the Julier pass all the way to Clavenna, where they were to take a parallel route north through the mountains to Curia. At a conservative estimate it was over a hundred and twenty miles along a narrow road easily blocked. If they arrived at all, it was unlikely to be any time soon. Another thousand cavalry, Moors commanded by the Danubian Probus, had followed a local shepherd who claimed he knew a sheep track passable by horses which snaked off to the east and came out to the north of the enemy. The existence of this path was dubious.
Several factors, all in the lap of the gods, had encouraged Gallienus to delay. The omens had been ambiguous, and there had been portents.
When they were in Clavenna, bees had swarmed around one of the standards. The priests had produced specious positive interpretations: bees laboured together for the common good; they never failed to obey the sole ruler of the hive. But Gallienus remembered the same had happened to the standards of the emperor Niger shortly before his army had been defeated by that of Severus.
Back in Comum, a priest of Jupiter had announced a dream he had said was sent by the god. In it a man in a toga had forced his way into the emperor’s encampment. He had been accompanied by two lares, the household divinities easily recognizable by the short dog-skin tunics they wore and the cornucopias in their hands. Near the praetorium, in front of the imperial standards, the lares had vanished. Left alone, the toga-clad figure had been beaten to death by the soldiers. The priest had produced his own exegesis of the dream. In every domestic shrine, the lares flanked the togate image of the genius of the household. Genialis was the adjective of genius. After initial success, the governor of Raetia would be deserted by the gods and killed.
Gallienus was unconvinced by this oneiromancy. For thirteen years his own genius had been worshipped across the imperium. The gods abandoning the genius chimed too closely with a thing that had been preying on his thoughts. Not since that day at Platonopolis with the old philosopher Plotinus, when his soul had been taken to these very Alps, had Gallienus sensed the presence of his divine companion. The emperor was sure Hercules had not left him for ever — like Antony in Alexandria, he would have heard the music — but the god was not with him now.
Amidst these supernatural concerns, Gallienus had been waiting for something else, something akin to divine intervention. It had appeared in the dead of the previous night in the form of the frumentarius called Venutus.
As dawn’s rose-red fingers lit the sky, Gallienus had led his army out to battle. His dispositions largely mirrored those of the enemy. A phalanx of heavy infantry was massed across the plain. On their right were four thousand drawn from all the four legions in the two Pannonian provinces. This mountain battle should hold nothing out of the ordinary for their commander, Proculus. He had been brought up in the Alpes Maritimae. Next to Proculus stood the veteran Prefect Volusianus with two thousand of his Praetorians. The left was held by Tacitus with a thousand shields drawn from the Italian Legio II Parthica, and another thousand from Legio V Macedonica marched west from Dacia. Like the enemy, they were all in six ranks, except on each wing, where the additional numbers allowed a formation packed twice as deep.
To provide covering shooting, the second line consisted of every one of the three thousand auxiliary foot archers the imperial field army possessed. The young Narbonensian protector Carus had charge of them.