Legio XVII: Roman Legion at War

by Thomas A. Timmes

  He started by detailing the preparations that were completed or still underway. He knew to the pound the amount of grain, fodder, and fuel the Army would transport; the number of pack animals and weight each would carry; and he knew with precision the history, linage and personnel strength of each of the four Legions. He even knew many of the Centurions by name and the campaigns in which they had participated. His ability to recall facts and data was astounding.

  “I expect,” he said, “about 10,000 Insubres to be in and near the fort at Acerrae and another 30,000 to 50,000, which could be mustered against us if the people in the region mobilized, particularly the Boii. To pin the Boii to their home territory, an Auxiliary force made up of Umbros, Veneti, and Cenomani under Roman leadership will march up the east coast to the Boii territory to keep them in place.”

  He reviewed the Insubres fighting tactics, body armor, weapons, and concluded with the warning not to underestimate their bravery and fighting skills.

  Marcellus said that their Senate-directed mission was to disestablish the fort at Acerrae by any means possible, demonstrate the power of Rome to maintain her supply routes, and encourage mutual cooperation with Rome. He said he would try to persuade the Insubres to abandon the fort peaceably, but held out little hope for success.

  He announced the departure time and march order of the four Legions and their baggage trains on the Via Aurelia. “The 3rd Legion and their trains will lead. I will march behind the 3rd Legion along with the command group, 100 cavalry troopers, and 20 mounted couriers. 4th Legion will be next with their baggage, then 5th and finally 6th Legion will provide rear security. Each Legion will also provide 10 empty wagons to follow their Legion in order to pick up those men unable to continue the march. I anticipate approximately 100 men per Legion will suffer debilitating blisters, thigh chaffing, and illness. These men will be returned to duty as soon as they are fit. The cavalry will maintain a 360 degree screen around the Legions with elements 10 hours out from the army to provide early warning.”

  His concept of the operation was straight forward. The Army would march approximately 15 miles per day for 23 days and establish a standard encampment each night. Naval ships would screen the coast keeping pace with the march and supply the Army every three days. Cavalry elements would maintain constant contact with the fleet. Ship board Auxiliaries would offload the supplies at predetermined ports and provide escort until it reached the Army in the field.

  If attacked enroute, Marcellus said he would select defensible terrain and initially put three Legions on line and hold one in reserve.

  Engineers would accompany the cavalry on the Via Aurelia to determine the status of the bridges enroute to the target. The Engineers were prepared to reinforce or build new bridges if required. Crossing the Po River will be a major undertaking and require vast resources if the existing bridges are out when the Army arrives. Marcellus directed the cavalry to identify a usable bridge over the Po and hold it secure once the Army approaches the area. The idea was to cross the Po upstream (west) of the joining of the Po and Adda and approach Acerrae from the west.

  “Once at the fort, I will offer a peaceful resolution to the Insubres. If refused, I plan to encircle the fort with a ditch 8’ across, 10’ deep, and 60’ away from the fort. Each Legion will be responsible for a portion of the ditch to man 24 hours a day. Each Legion will dig an encampment opposite one of the four walls of the fort.”

  “Should the Insubres attempt a breakout at their east facing and only gate, the opposing Legion and two closest would contain them in a half circle. The remaining Legion will assault the west wall opposite their gate to capture the fort or discourage any breakout attempt.”

  “While conducting the siege, supplies for the Army will be shipped by sea through the Ligurian port of Genua [Genoa] and be escorted to Acerrae by an onboard Auxiliary Legion mustered in for this purpose.”

  Marcellus said he fully expected the Insubres, Ligures, and Boii to mobilize up to 50,000 men and attack the army at Acerrae to break the siege or to attack the Roman supply base at Clastidium to pull the Army away from the siege. He then added, “Reinforcements are enroute to Clastidium to enable them to hold out for three days. This will allow time for us at Acerrae to abandon the siege and go to their rescue. As soon as we leave Acerrae, for Clastidium, the Insubres will probably resupply the fort, but there is no way to prevent it. If a small force were left at the fort to attempt to prevent the resupply, they would be slaughtered by the much larger Insubres force.”

  “Either we all stay at Acerrae or all depart for Clastidium. The Army would be ill advised to attempt to split its forces in the face of a larger enemy force.” Manius had vigorously argued this point with Marcellus and won the day. Other advisors wanted to leave a detachment of cavalry and infantry at Acerrae.

  Marcellus pointed out that their 22,000 Legionaries would be outnumbered more than 2 to 1 if the worst case scenario unfolds. Nonetheless, he expressed confidence in the outcome. At this point, he extended his gratitude to Manius for the recent equipment upgrades and felt that these changes along with solid Centurion leadership would carry the day.

  He concluded his two hour briefing by pointing out that this operation was not a punitive expedition against the Insubres or Liguri people, but against the fort and its interruption to commerce.

  Months earlier, Marcellus witnessed a demonstration on the use of war dogs and was greatly impressed. These molossus dogs [mastiff-type] from Epirus Greece were fitted with spiked collars and armor and were utterly fearless. They would attack man or beast on command. Marcellus obtained 20 dogs to accompany his Legions for this operation.

  The expedition progressed exactly as Marcellus predicted it would with few minor changes. The four Legions marched north two days later while the Auxiliaries marched east to Boii territory. Rough seas only once prevented the off loading of supplies; otherwise the resupply effort went fairly well. The Insubres failed to burn any of the three bridges over the Po River and the Army crossed as expected.

  Not surprisingly, the Insubres declined the offer to surrender the fort and a siege was initiated. Within 10 days, scouts told Marcellus that the Insubres, Ligures and Gaesatae were, indeed, mobilizing their forces and planning to attack Clastidium ~ exactly as foreseen!

  It appeared to Marcellus that the Insubres were not planning to actually besiege Clastidium, but rather merely threaten to do so, to draw the Romans away from Acerrae and then meet them in battle. His scouts estimated the Insubres force at about 30,000. Their leaders were Viridomarus [vere-e-doe-MAR-us], a Gaesatae, and Britomartus [bre-toe-MAR-us], an Insubres.

  Scouts noted that the ground at Clastidium was firm ~ no rain had fallen in weeks; the forest had been cleared within a mile of Clastidium and the ground was relatively flat. There was one commanding hill about 500 yards south of the fort and it was occupied and fortified by strong Gallic forces. The Roman fort was not under any imminent threat and had enough supplies to withstand a lengthy siege if one was initiated by the Insubres.

  The enemy continued to employ the Gallic slashing sword and small round disk shield while wearing minimal body armor. The exception was the Chieftain Viridomarus who wore exquisitely crafted body armor that appeared to be made of gold, silver, and precious stones. The scouts also noted that he appeared to wear what looked like a flexible metal shirt under the armor, but they could not see it well enough to provide further details.

  The scouts told Marcellus that the individual enemy soldiers appeared unruly, undisciplined, and untrained except for the Gaesatae. They reported seeing fighting within the Gallic camp and deserters slipping away. Despite these negative reports, Marcellus knew the enemy was fierce, inured to hardship, motivated, and would be fighting on his turf for his homeland. Defeating them would not be easy.

  Viridomarus also had his cavalry scout spying on the Romans. He felt the Romans would most likely abandon the siege at Acerrae once he threatened Clastidium. He planned to resupply the fort at A
cerrae as soon as the Romans were out of the area. If the Romans left a detachment at the fort to hinder the resupply, he felt his forces would easily overpower them.

  He knew the approximate strength of the Roman army and knew he had about a 2 to 1 advantage. But he also knew the individual Roman Legionaire was not to be underestimated. He envied their training, discipline, body armor, and weapons. He had met them before at Telamon three years ago and had witnessed firsthand the power of the Roman pila, the effectiveness of their short thrusting sword, the strength of their large protective shield, and their all encompassing personal body armor. He survived Telamon by mounting a loose horse and riding away before the army was totally defeated.

  Viridomarus knew he would have to plan the coming battle carefully and lamented the lack of training and discipline of his army. He knew they would revolt if he tried to institute the Roman method of rotating front line fighters or even to attack in lines like the Romans. They were too wild and independent for that kind of fighting discipline. No, he reasoned they would attack as a mob as they always did and trust that their individual valor and ferocity would win the day.

  His men were good fighters, but that was all. They refused to observe the most basic rules of society. They were by nature violent and cruel. They were totally out of place among the normal populace, but fit in well with others of their ilk. They knew, understood, and could instinctively follow the rule of violent, smash and grab behavior whether on the battlefield or in camp. In towns and villages they were as out of place as a normal villager would be in his army.

  He had heard of both Marcellus and Scipio and knew they were competent commanders. In the back of his mind, he began to doubt a Gallic victory. Then he remembered that in Gallic culture once the opposing leader was killed, the troops generally lost heart and their organization fell apart. Perhaps, he could seek out one of the Consuls and kill him in hand-to-hand combat and thus break the morale of the Roman Army.

  Viridomarus now had his plan and decided to make his move. He dispatched wagons full of food destined for Acerrae, but instructed them to swing wide around the entrenched Roman Army and wait until the Romans were at least a day’s march out before bringing the wagons to the fort. As best he could, he organized his forces into three large groups of 10,000 each.

  He then moved this unwieldy host to the area of the fortified hill, which was south of the Roman fort, and would serve as his command post. He put one group in the center with the hill to their immediate rear and the other two groups to the left and right of the center and a little forward of it. Gallic culture would not allow a reserve force. It would be a dishonor not to be first to fight the enemy. He had to commit everyone at the same time. His half moon formation allowed everyone to attack simultaneously and just might engulf the Romans in a deadly envelopment. He personally would use the height of the hill to look for one of the Consuls to fight.

  He knew these moves would be spotted immediately by the Roman scouts, but it did not matter. There was nothing to do now but wait for the Romans. To quicken the passage of time and maintain morale, he ordered large quantities of food and wine be taken from the surrounding villages and given to his troops. The camp fires burned late for the next several nights.

  When Scipio and Marcellus heard that the Gauls had completed their mobilization and were moving in the direction of the Roman supply base and not Acerrae, they decided it was time to move to where the enemy intended to fight them ~ Clastidium. Marcellus planned to stay well north of the Po River to avoid the marshes and swamps that dotted the region.

  Marcellus quickly abandoned the siege and began a relatively slow march to Clastidium, 50 miles and three days away. Riders were dispatched at frequent intervals to keep Rome, the port at Genua, and the forces at Clastidium informed of their activities.

  Marcellus wanted relatively fresh troops to arrive at Clastidium so he dictated an easy march pace of 12 miles per day with 10 minute rest break every hour. At the end of each day, the Legions dug their camp and ate and drank to maintain their strength for the coming battle. In the evenings, the Centurions, the backbone of the Army, talked to the Legionaries about tactics, matters of discipline, rotation procedures, and also checked the troops’ equipment. They talked of home, battle honors, and life after the army. The Romans were readying themselves for battle. For some, this would be their first battle and for others, their last.

  Marcellus gathered the Tribunes, Chiefs of Engineers, Calvary and Archers, and key Centurions to discuss the impending battle. His cavalry sent back a steady stream of information about the gathering Insubres including the size of the force, their activity, location, terrain, weather, equipment, morale, commanders, and intentions.

  Since the Gallic cavalry was about equal to the Roman cavalry in numbers, Manius recommended to Marcellus that he use his cavalry to fully occupy theirs to prevent them from influencing the infantry battle. When the scouts reported on the Gallic half moon formation with no reserve, Manius recommended that he approach the Gauls with two Legions abreast, the other two stacked up behind them with orders to be prepared to come alongside the lead Legions. By initially offering a small front to the Gauls, Manius hoped the Gauls would crowd together and not overlap his front by too much. When the Gauls were fully committed to their charge at the narrow Roman front, the plan was that Marcellus would maneuver the two trailing Legions to bring all four abreast and perhaps overlap the Gauls’ front. He knew this would put a tremendous strain initially on the two center Legions, but felt they could hold until the two Legions on the left and right wings could swing around and move in towards the center in what he hoped would be a tactical envelopment.

  Four Legions online would give the Romans an actual front of 2000 men stretching out for about three-quarters of a mile, but with no reserve. It was a gamble, but Marcellus and Manius felt that each Legion’s three-man deep lines of 500 men each for the Hastati, Principes, and Triarii, when rotated properly, would wear down the Gauls’ adrenaline powered charge.

  Manius planned that the three-man deep lines of the Hastati would rotate all three Legionaries twice and then pass through the rested and fresh Principes who would then take up the fight. When the Principes had rotated their three men three times, he would order the Hastati to move forward back to their original position in the front and repeat this process until the Gauls broke.

  He was relying on the maneuver discipline of the Army to successfully execute these difficult movements during battle. Now is when the hours of training and discipline would pay off. These same maneuvers, passing the Principes through the Hastati and then back again, had been practiced endlessly.

  What Marcellus did not foresee was that Viridomarus would be looking for him!

  The Romans dug in their final camp about three hours from Clastidium and the waiting Gallic Army. For the preceding two days, Marcellus had his scouts out looking for an advantageous location to fight the battle. His instruction to the scouts was to find an area less than a mile wide with swamps, hills, or thick woods on both flanks. Marcellus was looking for a site that would provide natural protection to his flanks and offer a narrow front to the attacking Gauls.

  While the Army slept, Marcellus arose in the dark the day of the battle and followed the scouts on horseback to an area they tentatively selected for the battle. It was about half a mile from the sleeping Gauls and appeared to offer exactly what Marcellus was looking for. The flanks were protected with a thick stand of oak, cypress, and larch on one side and a rocky outcrop on the other. The terrain resembled a funnel and he planned to position his soldiers at the small end. The large open end sloping downward would offer the Gauls a tempting avenue of approach. He hoped that in their rush to attack, they may not realize that the terrain would be forcing them into an ever tightening mass and his waiting Legions. It was not perfect, but it would do.

  The Romans were up by 0400, ate a hardy meal, and were on the march by 0600 in their battle formation of two Legions up with the other two
immediately behind them. Cavalry elements acted as a rear guard. Walking in this configuration was slow and required constant stopping to straighten the lines as the terrain separated units and slowed their advance.

  The Gauls were aware that the Romans were on the march and readied their Army. Meals were hastily eaten and body paint was copiously applied. Fires still burned to ward off the lingering morning chill. The morning sun was a welcomed relief.

  By 1100, the leading elements of the Roman Army appeared in the distance. To the Gauls, the approaching Army appeared like a small, shinny gray rock with hints of red sprinkled throughout. The Gauls looked about at their own Army and realized that they were much greater in number and by their account, much better fighters.

  As they got closer, Viridomarus could only see the leading two Legions and immediately suspected Roman deception. He envisioned the other two Legions were maneuvering to get behind his forces. He quickly ordered his cavalry to search the area to the rear to find the missing Legions and began to consider his options to handle this change of plans. His mind eased when he realized that if the Roman commander was foolish enough to split his forces in the face of superior numbers, he was strong enough to defeat each part in turn. After 30 minutes, the scouts returned and reported no Romans to the rear. Still Viridomarus worried.

  The Legions advanced on the Gauls until only half a mile separated the two Armies across an open field. Manius and the Tribunes then quickly maneuvered the Legions into their fighting positions and ordered that everyone drink plenty of water and sit down. The Centurions ensured that all complied.

  Figure 8 Legions arrayed for battle

  Shortly after settling in to their initial battle site at the opening of the funnel, Marcellus ordered the 300 Velites to advance and to begin harassing the enemy. He also ordered the cavalry forward to create a dust cloud to mask his movements.