Battle of Dertosa

The Battle of Dertosa, also known as the Battle of Ibera, was fought in the spring of 215 BC on the south bank of the Ebro River across from the town of Dertosa. A Roman army, under the command of Gnaeus Cornelius Scipio Calvus and Publius Cornelius Scipio defeated a similarly sized Carthaginian army under Hasdrubal Barca. The Romans, under Gnaeus Scipio, had established themselves in Hispania after winning the Battle of Cissa in 218 BC. The expedition of Hasdrubal Barca to evict them had ended in the defeat of the Iberian contingent of the Carthaginian navy at the Battle of Ebro River in 217 BC. Hasdrubal launched another expedition in 215 BC, but the defeat at Dertosa cost the Carthaginians a chance to reinforce Hannibal at a critical juncture, and the Romans gained the initiative in Hispania. The Scipio brothers continued with their policy of subjugating the Iberian tribes and raiding Carthaginian possessions. After losing of most of his field army, Hasdrubal had to be reinforced with the army that was to sail to Italy and reinforce Hannibal. Thus, by winning this battle, the Scipios had indirectly prevented the situation in Italy from getting worse in addition to improving their own situation in Iberia. This battle also demonstrates the danger of implementing the double envelopment tactic.

Italy
After the Battle of Cannae, several towns in Campania, Samnium, Lucania, Apulia and Bruttium had defected to Carthage. Hannibal spent the period 216-215 BC trying to secure a seaport to ease his communication with Carthage by attacking Neapolis, Cumae and Nola, all unsuccessfully. A detachment under Mago Barca had secured objectives in Lucania and Bruttium. Leaving Hanno the Elder in command of this army in Bruttium, Mago sailed to Carthage to obtain reinforcements.

The Romans had fielded several armies, which followed a strategy of avoiding Hannibal in the open field and striking at his allies whenever possible. The main Roman army under the dictator M. Julius Pera was guarding the direct approach to Rome in southern Latinum. Marcus Claudius Marcellus had battled Hannibal at Nola and also prevented Neapolis from falling to the Carthaginians. The Master of Horse, T. Sempronius Gracchus, was on the field with a third army in Lucania. Other legions guarded against any Gaulish uprisings in north Italy.

Sardinia
The legion posted in Sardinia suffered from sickness. The praetor, Muscius Scavola, had to collect pay and provisions for the troops locally. This had caused unrest among the Sardinians, and Hampsicora, a Sardinian chieftain, was fomenting rebellion among the locals and had requested Carthaginian aid.

Africa
Carthage raised 15,000 infantry, 1,200 cavalry and 20 elephants under the command of Mago, which was to sail to Italy escorted by 60 quinqueremes. Upon receiving the appeal from Sardinia, a similar sized army was raised under Hasdrubal the Bald, for an expedition to Sardinia.

Iberia
Hasdrubal had been on the defensive since the defeat of his fleet at Battle of Ebro River in the spring of 217 BC. He had left Boaster, a subordinate commander, with a force to guard the Ebro line against any Roman encroachment. Boaster had retreated when the Romans had crossed the Ebro. Furthermore, he was tricked into surrendering the Iberian tribal hostages held at Saguntum to the Romans by an Iberian chieftain named Abylix. This caused revolts in Barcid Iberia, especially among the Trudetani tribe near Gades in 216 BC. Hasdrubal received 4,000 foot and 500 horsemen, with orders to march to Italy after securing Iberia. The better part of 216 BC was spent in subduing the Iberian tribes, with little effort made to confront the Romans.

Gnaeus Scipio had received 8,000 reinforcements under his brother Publius Scipio after the battle of Ebro River. The brothers enjoyed proconsular rank, and exercised joint command. The brothers adopted an aggressive naval strategy given the destruction of the Carthaginian navy, raiding Barcid possessions in Iberia and Balearic Islands. The Scipios also recruited auxiliary troops from Iberian tribes, garrisoned towns to expand their operational sphere, consolidated their hold north of the Ebro River and dealt with tribal unrest there. They also encouraged Iberian tribes friendly with the Romans to raid tribes loyal to Carthage beyond the Ebro.

Prelude
In early 215 BC The Romans crossed the Ebro River in force and laid siege to Ibera, a small Iberian town allied to Carthage. Leaving Himilco in charge at Cartagena, Hasdrubal marched north with his field army to the Ebro. However, he chose not to cross the Ebro to raid the Roman possessions nor did he attack the Roman army besieging Ibera. The Carthaginian army besieged a town allied with the Romans across Dertosa instead. The Scipios lifted their siege and moved to engage Hasdrubal. Thus, Hasdrubal had gained the strategic initiative. He had aided his allies by forcing the Romans to lift their siege and face the Carthaginian army on a site of his own choosing. The opposing armies encamped on a plain between Ibera and Dertosa within five miles of each other. After five days of skirmishing, the commanders drew out their armies for battle.

Opposing Armies
The Roman infantry consisted of two Roman legions with a total of 10,000 soldiers, and 18,000 allied Italian troops. The cavalry was made up of 600 Roman and 1,800 Italian heavy horsemen. The Romans also had recruited an auxiliary force of 2,000 Iberian footmen and 400 heavy horsemen.

Hasdrubal had 15,000 Libyan spearmen, 1,000 mercenaries (mostly Ligurians from Italy) and 8,000 Iberian troops for his infantry. The Carthaginian cavalry was made up of 450 Libyan/Punic and 1,200 Iberian heavy horsemen and 2,300 light Numidian horsemen. The Carthaginian army also had 20 elephants and 1,000 Balearic slingers.

Deployment before Battle
The Romans posted their troops in their traditional manner, with the cavalry on the wings and the infantry in the center. The Roman and Iberian horse was placed on the right wing, the allied Italian horse on the left wing. The infantry line had the Italian troops on the wings next to the cavalry, and the Roman legions were posted in the center. Two thousand Roman/Italian troops and the Iberian infantry guarded the Roman camp.

Hasdrubal placed the Libyan and Iberian horse on his left wing facing the Roman/Iberian horse, and the Numidian light horse on his right wing facing the allied Italian horsemen. Next to the Iberian cavalry contingent, Hasdrubal placed a phalanx of Libyan infantry, backed up by mercenaries, facing the Italian foot, and another phalanx of Libyan foot was placed next to the Numidian horsemen on the Carthaginian right wing, also facing Italian foot. Between the Libyan infantry phalanxes in the center of the Carthaginian infantry line, facing the Roman legions, was a thinned out Iberian infantry line. The elephants were divided into two groups of 10 and placed in front of the cavalry on both of the wings. The Balearic slingers formed a skirmish line in front of the infantry. Two to three thousand troops were left to guard the Carthaginian camp.

Phase 1
After a brief skirmish between light troops, the Roman legions in the center charged the thinned out line of Iberian infantry opposite them, and having the advantage of both number (10,000 against 8,000) and formation depth, drove back the Iberians almost instantly. However, this is an integral part of the double envelopment tactic Hasdrubal was trying to implement. The Carthaginian elephants placed on both the wings charged the Roman and Italian cavalry opposite them. The charge proved ineffective, the Italian and Roman horsemen were not disrupted, and the elephants played no further role in the battle. The Italian infantry formations closed with the Libyan formations opposite then in support of the Romans attacking the Iberians.

Phase 2
The Libyans and mercenaries placed on the flanks of the hard pressed Iberians charged the Italian infantry opposite them, and despite their advantage in numbers (16,000 against 18,000), the Italians were pushed back. Unlike Cannae, the Libyans did not outflank the Romans. The Carthaginian cavalry placed on the wings, on the flank of the Libyans closed with the Roman and Italian horsemen opposite them. Despite having the advantage in numbers on both wings (1,600 Libyan/Punic and Iberians faced 1,000 Roman/Spaniards on the left of the Carthaginian line and 2,300 Numidians faced 1,800 Italian horsemen on the right of the Carthaginian line), the Carthaginian horsemen were unable to drive the Romans from the battlefield. An indecisive skirmish developed on the both wings of the armies between the opposing cavalry, with neither side gaining any advantage. At this point, the Iberian infantry on the Carthaginian center line collapsed, and began to flee the battle.

Phase 3
At Cannae, the center of the Carthaginian infantry line had also collapsed under Roman infantry assault. But Hannibal had managed to win the battle as his infantry had outflanked the Romans on both sides, and his cavalry, after driving their Roman opponents from the field, had attacked the Roman infantry from the rear (or like the battle of Trebia where Mago's ambushing troops were also able to attack the Roman infantry in the rear). Hasdrubal had no ambush in place at Dertosa, but the Libyans had been driving the Italian infantry back when the Iberians at the center had collapsed.

The Carthaginian cavalry, seeing their infantry center break and run, broke off their skirmishing with their Roman counterparts and also fled the battlefield. The Roman infantry, after scattering the Iberians, returned to help the Italian infantry. The Libyan infantry managed to put up a hard resistance, inflicting and suffering heavy casualties before being routed.

Aftermath
Hasdrubal survived the battle with most of his elephants and cavalry, and a few infantry (mostly Iberians). The Roman pursuit was not vigorous enough to repeat their success after the Battle of Cissa. The Romans managed to storm the Carthaginian camp, after Hasdrubal had hastily evacuated his soldiers. The provisions and booty fell into the hands of the victorious Romans. The shattered Carthaginian army retired to Cartagena, leaving the Romans firmly established south of the Ebro.

Hasdrubal would be reinforced by two armies under Mago Barca and Hasdrubal Gisco to keep the Romans in check and keep the Carthaginian possessions in Iberia under control. The Carthaginians would not mount any effective campaigns north of the Ebro again, and would be fated to battle the Romans until 205 BC for the control of Iberia with varying success.

The Scipio brothers did not mount a vigorous pursuit or an immediate campaign against the Carthaginians immediately after their victory. They chose to follow their strategy of mounting raids, instigating Iberian tribes to rebel, and building up their power base. The Scipios would receive no reinforcements from Italy for the remainder of their command in Iberia. They would fight the Barca brothers and Gisco with varying results until 212 BC, when they launched a major campaign leading to the Battle of the Upper Baetis.

Importance
Hasdrubal had tried to imitate the tactics used by Hannibal at Cannae. While Hannibal had brought about a spectacular victory, Hasdrubal had suffered a shattering defeat. Some of the factors for this contrasting result are:


 * Hannibal had a better army and staff officers, and better control over his troops. The Iberians of Hasdrubal were lukewarm about leaving Iberia, which may have affected morale.


 * The skill of the Carthaginian staff officers at Cannae was demonstrated by the maneuvers of Hasdrubal (not Hasdrubal Barca), commanding the heavy cavalry. His unit charged and broke the Roman horse, regrouped, crossed the battlefield to attack the Italian horse from the rear, again regrouped, then attacked the Roman infantry from the rear. These were extremely complex moves orchestrated with flawless efficiency, a tribute to the skill of the troops and their commander. Hasdrubal Barca did not have such assets at Dertosa.


 * Hannibal had a decisive advantage in cavalry (10,000 against 6,000) at Cannae and took advantage of this to the fullest. Hasdrubal had a slight advantage (4,000 against 2,800), but failed to take any advantage or devise any formation to gain the upper hand.


 * Hannibal had no elephants at Cannae. Hasdrubal had 20, but he gained no advantage from his use of them.

Strategic importance
Although the Battle of Dertosa is not given the same importance as the Battle of the Metaurus, it had a critical influence on the strategic course of the war.


 * Had Hasdrubal won the battle, there would have been at least four Carthaginian armies operating in Italy by 214 BC, those of Hasdrubal, Hannibal, Mago and Hanno the Elder.


 * The cornerstone of the strategy which Hamilcar Barca had planned depended on the undisputed control of Iberia by the Barcids, and the ability to draw manpower and wealth from it. The defeat caused Carthage to send Mago Barca, along with Hasdrubal Gisco, a political rival of the Barcids to Iberia. This ended the Barcid domination, with far reaching consequences. In addition, Hannibal never managed to receive further reinforcements from Iberia.


 * The Romans gained the initiative in Iberia, which caused a drain of resources better employed elsewhere. Consequently, Mago was sent to Iberia with the reinforcements meant for Hannibal.


 * Although Hannibal would receive 4,000 Numidian Horse and 40 elephants in 215 BC, these were pitiful compared to the 17,000 soldiers that would be lost in Sardinia and the 28,000 soldiers that would be tied up in Sicily later. In short, the defeat at Dertosa took away most of the political capital Hannibal had won in Carthage through his victory at Cannae.