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 the brothers Gnaeus 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. Hasdrubal Barca's expedition 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.

Primary sources

The main source for almost every aspect of the Punic Wars is the historian Polybius, a Greek sent to Rome in 167 BC as a hostage. His works include a now-lost manual on military tactics, but he is now known for The Histories, written sometime after 146 BC. Polybius's work is considered broadly objective and largely neutral as between Carthaginian and Roman points of view. Polybius was an analytical historian and wherever possible personally interviewed participants, from both sides, in the events he wrote about.
The accuracy of Polybius's account has been much debated over the past 150 years, but the modern consensus is to accept it largely at face value, and the details of the war in modern sources are largely based on interpretations of Polybius's account. The modern historian Andrew Curry sees Polybius as being "fairly reliable"; while Craige Champion describes him as "a remarkably well-informed, industrious, and insightful historian".
Other, later, ancient histories of the war exist, although often in fragmentary or summary form. Modern historians usually take into account the writings of various Roman annalists, some contemporary; the Sicilian Greek Diodorus Siculus; the later Roman historians Livy, Plutarch, Appian and Dio Cassius. The classicist Adrian Goldsworthy states "Polybius' account is usually to be preferred when it differs with any of our other accounts". Other sources include inscriptions, archaeological evidence and empirical evidence from reconstructions such as the trireme Olympias.

Background

Pre-war

The First Punic War was fought between Carthage and Rome, the two main powers of the western Mediterranean in the 3rd century BC struggled for supremacy primarily on the Mediterranean island of Sicily and its surrounding waters, and also in North Africa. The war lasted for lasted for 23 years, from 264 to 241 BC, until the Carthaginians were defeated. The Treaty of Lutatius was signed by which Carthage evacuated Sicily and paid an indemnity of 3,200 talents over ten years. Four years later Rome seized Sardinia and Corsica on a cynical pretence and imposed an additional 1,200 talent indemnity. The seizure of Sardinia and Corsica by Rome and the additional indemnity fuelled resentment in Carthage. Polybius considered this act of bad faith by the Romans to be the single greatest cause of war with Carthage breaking out again nineteen years later.
Shortly after Rome's breach of the treaty the leading Carthaginian general Hamilcar Barca led many of his veterans on an expedition to expand Carthaginian holdings in south-east Iberia ; this was to become a quasi-monarchial, autonomous Barcid fiefdom. Carthage gained silver mines, agricultural wealth, manpower, military facilities such as shipyards and territorial depth which encouraged it to stand up to future Roman demands. Hamilcar ruled as a viceroy and was succeeded by his son-in-law, Hasdrubal, in the early 220s BC and then his son, Hannibal, in 221 BC. In 226 BC the Ebro Treaty was agreed, specifying the Ebro River as the northern boundary of the Carthaginian sphere of influence. A little later Rome made a separate treaty with the city of Saguntum, well south of the Ebro. In 219 BC a Carthaginian army under Hannibal besieged, captured and sacked Saguntum. In spring 219 BC Rome declared war on Carthage.

Rome invades Iberia

In 218 BC the Romans raised an army to campaign in Iberia under the brothers Gnaeus and Publius Scipio. The major Gallic tribes in Cisalpine Gaul attacked the Romans, capturing several towns and ambushing a Roman army. The Roman Senate detached one Roman and one allied legion from the force intended for Iberia to send to the region. The Scipios had to raise fresh troops to replace these and thus could not set out for Iberia until September.
Meanwhile, Hannibal assembled a Carthaginian army in New Carthage and entered Gaul, taking an inland route to avoid the Roman allies along the coast. Hannibal left his brother Hasdrubal Barca in charge of Carthaginian interests in Iberia. The Roman fleet carrying the Scipio brothers' army landed at Rome's ally Massalia at the mouth of the Rhone at the same time as Hannibal was fighting his way across the river against a force of local Allobroges at the Battle of Rhone Crossing. Hannibal evaded the Romans and Gnaeus Scipio continued to Iberia with the Roman army; Publius returned to Rome. The Carthaginians crossed the Alps early in 217 BC, taking the Romans by surprise and causing them to cancel their main campaign planned for the year, an invasion of Africa.

Carthage reacts

Gnaeus Scipio continued on from Massala to Iberia, landing his army in the autumn of 218 BC at Cissa and winning support among the local tribes. The Carthaginian commander in the area, Hanno, refused to wait for Carthaginian reinforcements under Hasdrubal, attacked Scipio at the Battle of Cissa in late 218 BC and was defeated. In 217 BC, the Carthaginians moved to engage the combined Roman and Massalian fleet at the Battle of Ebro River. The 40 Carthaginian and Iberian vessels were beaten by 55 Roman and Massalian ships in the second naval engagement of the war, with 29 Carthaginian ships lost. Carthaginian forces retreated, but the Romans remained confined to the area between the Ebro and Pyrenees. The Roman lodgement was preventing the Carthaginians from sending reinforcements from Iberia to Hannibal or to the insurgent Gauls in northern Italy.
In 217 BC Publius Scipio joined his brother in Iberia.
In 217 BC, Hasdrubal launched a joint operation, advancing into the Roman controlled area in close cooperation with a fleet of 40 Carthaginian and Iberian quinqueremes. The naval component was defeated by 55 Roman and Massalian vessels at the Battle of Ebro River, with 29 Carthaginian ships were lost. In the aftermath the Carthaginian forces retreated, but the Romans remained confined to the area between the Ebro and Pyrenees.
Hasdrubal received orders from Carthage to move into Italy and join up with Hannibal to put pressure on the Romans in their homeland. Hasdrubal demurred, arguing that Carthaginian authority over the Spanish tribes was too fragile and the Roman forces in the area too strong for him to execute the planned movement. Hasdrubal 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 by an Iberian chieftain named Abylix into surrendering the Iberian tribal hostages held at Saguntum to the Romans. This caused revolts in Carthaginian Iberia, especially among the Turdetani tribe near Gades in 216 BC. Hasdrubal received 4,000 foot and 500 horsemen as reinforcements, with orders to march to Italy after securing Iberia. The better part of 216 BC was spent in subduing the Iberian tribes; little effort was made to confront the Romans.

Prelude

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 the 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 Rome to raid tribes beyond the Ebro who were loyal to Carthage.
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. Instead, the Carthaginian army besieged a town allied with the Romans across Dertosa. 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 forces

Roman

Most male Roman citizens were eligible for military service and would serve as infantry, a better-off minority providing a cavalry component. Traditionally, when at war the Romans would raise two legions, each of 4,200 infantry and 300 cavalry. A few infantry served as javelin-armed skirmishers. The balance were equipped as heavy infantry, with body armour, a large shield and short thrusting swords. They were divided into three ranks, of which the front rank also carried two javelins, while the second and third ranks had a thrusting spear instead. Both legionary sub-units and individual legionaries fought in relatively open order. It was the long-standing Roman procedure to elect two men each year, known as consuls, to each lead an army. An army was usually formed by combining a Roman legion with a similarly sized and equipped legion provided by their Latin allies.
The Roman infantry consisted of two legionss, with a total of 10,000 soldiers, and 18,000 Latin allies. The cavalry comprised 600 Roman and 1,800 Italian heavy cavalry. The Romans also recruited an auxiliary force of 2,000 Iberian infantry and 400 heavy cavalry.

Carthaginian

Carthage usually recruited foreigners to make up its army. Many would be from North Africa which provided several types of fighters including: close-order infantry equipped with large shields, helmets, short swords and long thrusting spears; javelin-armed light infantry skirmishers; close-order shock cavalry carrying spears; and light cavalry skirmishers who threw javelins from a distance and avoided close combat. Both Spain and Gaul provided large numbers of experienced infantry; unarmoured troops who would charge ferociously, but had a reputation for breaking off if a combat was protracted. The close order Libyan infantry and citizen-militia from North Africa would fight in a tightly packed formation known as a phalanx. The Libyans were usually well trained but the citizen-militia were notoriously ill-trained and ill-disciplined. Slingers were frequently recruited from the Balearic Islands. The Carthaginians also employed war elephants; North Africa had indigenous African forest elephants at the time.
Hasdrubal had 15,000 North African spearmen, 8,000 Iberians, 1,000 mercenaries and 1,000 Balearic slingers for his infantry. The Carthaginian cavalry comprised 450 North African and 1,200 Iberian heavy cavalry and 2,300 light cavalry from Numidia. The Carthaginian army also had 20 war elephants.

Battle

Deployment

were usually preceded by the two armies camping a mile or two apart for days or weeks; sometimes forming up in battle order each day. If neither commander could see an advantage, both sides might march off without engaging. Forming up in battle order was a complicated and premeditated affair, which took several hours. Infantry were usually positioned in the centre of the battle line, with light infantry skirmishers to their front and cavalry on each flank. Many battles were decided when one side's infantry force was attacked in the flank or rear and they were partially or wholly enveloped.
The Romans posted their troops in their traditional manner, with the cavalry on the wings and the infantry in the center. The combined Roman and Iberian horse was placed on the right wing, with 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. The Roman camp was guarded by the Iberian infantry and 2,000 Roman/Italian troops.
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 two cavalry contingents, in both cases facing the Italian foot, Hasdrubal placed a phalanx of Libyan infantry, backed up by mercenaries. In the center of the Carthaginian infantry line, between the Libyan infantry phalanxes and facing the Roman legions, was a thinned out line of Iberian infantry. 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 the light troops, the Roman legions in the center advanced against the line of Iberian infantry opposite them and, having the advantage of both number and formation depth, drove them back almost instantly. However, this was an integral part of the double envelopment tactic that Hasdrubal was trying to implement. The Carthaginian elephants placed on both 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. In support of the Romans attacking the Iberians, the Italian infantry formations closed with the Libyan formations opposite them.

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, 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, the Carthaginian horsemen were unable to drive the Romans from the battlefield. An indecisive skirmish developed on both wings of the armies between the opposing cavalry, with neither side gaining any advantage. At this point, the Iberian infantry forming the Carthaginian center 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 because his center had resisted the pressure, allowing the rest of his infantry outflank the Romans on both sides; his cavalry, after driving their Roman opponents from the field, had attacked the Roman infantry from the rear. In comparison, Hasdrubal had no ambush in place at Dertosa, his center had collapsed, and the Libyans had been driving the Italian infantry back when the Iberians at the center had retired.
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. 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.
To keep the Romans in check and keep the Carthaginian possessions in Iberia under control, Hasdrubal would be reinforced by armies under Mago Barca and Hasdrubal Gisco. 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.

Analysis

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:
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.