The Battle of the Rhône Crossing was a battle during the Second Punic War in September of 218 BC. Hannibal marched on the Italian Alps, and an army of Gallic Volcae attacked the Carthaginian army on the east bank of the Rhône. The Roman army camped near Massalia. The Volcae tried to prevent the Carthaginians from crossing the Alps and invading Italy.
Before they crossed the river, the Carthaginians sent a detachment to cross upriver, under Hanno, son of Bomilcar, and took up position behind the Gauls. Once the detachment was in place, Hannibal crossed the river with the main contingent of his army. As the Gauls massed to oppose Hannibal, Hanno attacked their rear and routed the Volcae army. This was Hannibal's first major battle (victory) outside of the Iberian Peninsula. It gave him an unopposed path to the Alps and into Italy.
Background
Pre-war
Carthage and Rome fought through the First Punic War primarily for supremacy in North Africa and on the Mediterranean island of Sicily and in its surrounding waters. The war lasted 23 years, from 264 until 241 BC. It ended with the Treaty of Lutatius, under which Carthage evacuated Sicily and paid an indemnity of 3,200 talents over ten years. Four years later, Rome seized Sardinia and Corsica and imposed a further 1,200 talent indemnity. These seizures and the additional indemnity fuelled resentment in Carthage. Polybius considered this act of bad faith by the Romans as the single greatest cause of the war with Carthage breaking out again nineteen years later.
Shortly after the Roman breached the treaty, Carthaginian general Hamilcar Barca led many of his veterans to expand Carthaginian holdings in south-east Iberia (modern Spain and Portugal). 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 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 Romans and Carthaginians signed the Ebro Treaty, declaring the Ebro River the northern boundary of the Carthaginian sphere of influence. Rome later made a separate treaty with Saguntum, south of the Ebro. In 218 BC, a Carthaginian army under Hannibal besieged, captured and sacked Saguntum. In spring 219 BC Rome declared war on Carthage.
Roman preparations and strategy
As Hannibal had anticipated, Rome expected the Carthaginians to fight a defensive war with minor attacks in Sicily, and therefore planned to attack both Spain and Africa. Understanding that a simultaneous strike against both Spain and Carthage at the earliest opportunity would give Hannibal the opportunity to defeat their armies in detail, they planned first for Scipio to engage Hannibal either north of the Ebro or east of the Pyrenées or the Rhône, where he could receive aid from allied Iberians or Gauls, and after Scipio had located and engaged Hannibal's forces, Sempronius, stationed in Sicily, would invade Africa.
Due to the size and defences of the city of Carthage, it would take the Romans months to starve the city out through siege and blockade. Additionally, relief armies would have to be beaten off during the siege. Since 241 BC, Rome had not negotiated but instead dictated terms to Carthage, which had always backed down. The Romans most likely expected that Carthage was bluffing when it refused to accept terms, and would capitulate as soon a Roman army blockaded the city, or roused the Numidians and Libyans to rebel against Carthage. Carthage came close to capitulation in 256–55 BC when Marcus Atilius Regulus invaded Africa. If Scipio could keep Hannibal away from Africa for long enough, perhaps Sempronius could repeat the feat, or the opponents of the Barcids, some of whom had relations with Roman senators might assume power, or trigger the recall of Hannibal, and accept Roman demands.
The Roman navy had been mobilized in 219 BC, fielding 220 quinqueremes for the Second Illyrian War. It was the long-standing Roman procedure to elect two men each year, known as consuls, to each lead an army, and Rome in 218 BC decided to raise two consular armies and strike simultaneously at Iberia and Africa.
Consul Tiberius Sempronius Longus received instructions to sail for Africa escorted by 160 quinqueremes, with four legions: two Roman legions and two allied legions consisting of 8,000 Roman and 16,000 allied infantry, and 600 Roman and 1,800 allied horses.
Publius Cornelius Scipio, the other consul for 218 BC, received orders from the Senate to confront Hannibal in the theatre of either the Ebro or the Pyrenées. and received four cases legions (8,000 Roman and 14,000 allied infantry, 600 Roman and 1,600 allied horse) and was to sail for Iberia escorted by 60 ships. His brother Gnaeus accompanied him as a legate.
The consuls took office in March and began organizing their forces. However, before Scipio's army was ready, the Boii and the Insubres, two major Gallic tribes in Cisalpine Gaul (modern northern Italy), antagonized when several Roman colonies were established on traditionally Gallic territory, and perhaps enticed by agents of Hannibal, attacked the Roman colonies of Placentia and Cremona, causing the Romans to flee to Mutina, which the Gauls then besieged. This probably occurred in April or May of 218 BC.
The Roman Senate prioritized the defence of Italy over the overseas expedition, and Praetor Peregrinus Lucius Manlius Vulcavalrus, with 600 Roman horses, 10,000 allied infantry and 1,000 allied cavalries detached from Scipio's army, marched from Ariminium towards Cisalpine Gaul to the aid of the besieged Romans.
War in Cisalpine Gaul
The army of Manlius was ambushed twice as it marched from Ariminum towards Mutina, losing 1,200 men and six standards. Although they did relieve Mutina, the army fell under a loose siege a few miles from Mutina at Tannetum. The Roman Senate once more took one Roman and one allied legion (10,000 men) from the army of Scipio and sent them to the Po valley under the command of Praetor Urbanus Gaius Atillius Serranus. As Atillius neared Tannetum, the Gauls retreated without a fight, and the Romans spent the summer of 218 BC recovering and fortifying Placentia and Cremona, probably in a two-month-long operation.
Sempronius remained in Rome until June/July. His army acted as a strategic reserve should more troops be needed in Cisalpine Gaul. Rome did not respond to the Carthaginian naval raids against Sicily and Lipari. Hannibal's passivity and non-threatening defensive dispositions during March through May probably influenced this decision by reinforcing the Roman perception that they were fighting a repeat of the first war and the initiative lay with them. The Romans did not believe Hannibal would invade Italy, when they received the news, probably in July, that Hannibal had crossed the Ebro, they probably assumed Hannibal's Catalonia campaign was part of securing Spain by subduing pro-Roman tribes and creating a forward base. The Senate did not change the plan, Sempronius moved his forces to Sicily as planned, where he continued to prepare his African expedition at Lilybaeum and defend Sicily and Italy from several Carthaginian naval raids. Scipio raised and trained two Roman legions and awaited for allied troops to arrive in Rome to replace the troops taken from him, and thus could not set out for Iberia until September. and as a result, the departure of Scipio was delayed by two to three months.
Punic preparations and strategy
During the First Punic War, the Romans dictated the pace of the war by taking the initiative and attacked Carthaginian positions. Carthage normally reacted to the Roman attacks. Hannibal planned to carry the war overland to Italy to deter the expected Roman invasion of Spain and Africa and dismember the Roman confederation. Hannibal's overland approach to Italy was a high-risk strategy, and failure might have cost Carthage the war, but he was forced to choose this option given the strategic limitations the Carthaginian empire faced in 218 BC, and it had a chance of succeeding. An overland invasion would have the advantage of surprise while sailing to Italy might have been faster and safer from hazards of a land march, but Roman naval dominance increased the risk to Hannibal's armada, of crippling losses from Roman naval attacks despite Carthaginian warship escorts, and ships could also be lost in storms en route to Italy. Fleets normally sailed along the coast and beached at night or after every 2/3 days for victuals. Carthage had no bases on the coast between the Balearic Islands and Italy, which was dominated by Roman ally Massalia and her colonies and wild Ligurians, and the Romans controlled Sardinia, Corsica, and Sicily, and thus effectively controlled the coast between Spain and Italy, so a sea voyage would have been more dangerous than a land route. Last, enough horse transports to carry 9,000 horses to Italy might not have been available for Hannibal.
Hannibal needed to time his movements carefully to keep the Romans in the dark. If the Romans got a hint of his intentions, they had enough resources to fight a multi-front war, by sending one army to block his army at the Pyrenees, stationing a strong force in Cisalpine Gaul, and invading Africa with another, or stand on the defensive with overwhelming forces. After the successful conclusion of the Siege of Saguntum, Hannibal did nothing to provoke the Romans, dismissed his army, and did not immediately march for Italy in the spring of 218BC after he received the news of the war. He spent the months of March to May strengthening the defences of Spain and Africa by garrisoning these areas which were not threatening to the Roman mainland and served a dual purpose, along with securing the areas against the expected Roman invasion it also reinforced the Roman perception that Carthage would fight a defensive war along the lines of the First Punic War, so the overland invasion caught Rome off guard.
Carthaginian deployments
Hannibal stationed Hasdrubal Barca, his younger brother, at the head of 12,650 infantry: 2,550 cavalries (11,580 African foot, 300 Ligurians, 500 Balearic slingers, 450 Liby-Phoenician 300 Spanish Ilergetes, and 1,800 Numidian horse from the Masaesyli, Massylii, Mauri and Maccoei tribes) and 21 elephants to guard the Carthaginian possession horses of the Ebro. Hannibal sent 20,000 Iberian soldiers to Africa (including 13,850 and 1,200-foot horses from the Mastiani, Thersitae, Olcades and Orestes tribes, and 870 Balearic slingers), and 4,000 soldiers garrisoning Carthage itself, probably between March-May. Hasdrubal and Carthage could raise additional soldiers if needed to fight Romans, and Carthage was unlikely to fall to a single consular army in a few months.
Hannibal left Cartagena in late May or early June, timing his departure to allow the spring flooding of Spanish rivers to subside. He ensured the availability of food and fodder along the way, and after receiving envoys from Gallic tribes from the Po valley, who assured him of their willingness to cooperate against the Romans. Hannibal's army consisted of either 90,000 foot and 12,000 cavalries, or 77,000 foot and 10,000 horse, or with 26,000 foot and 10,000 horse, and 37 elephants. The elephants were reported by Appian. There is no mention of the elephants by Polybius or Livy, so there is speculation that the elephants may have been carried to Emporiae by sea. The Iberian contingent of the Punic navy, which numbered 50 quinqueremes (only 32 were manned) and five triremes, remained in Iberian waters, having shadowed Hannibal's army for some way. The army probably marched in smaller columns along a 5-7 miles long stretch and the 290 miles march to the Ebro, during which they crossed the Sucor river, and five major streams, which were uneventful, and the river was reached in the middle of July.
Carthaginian campaign across the Ebro
The Carthaginian Army crossed the Ebro River in three columns. The northernmost crossed at the confluence of the Ebro and Sicoris River and then proceeded along the river valley into the mountain countries. The central column crossed the Ebro at the oppidum of Mora and marched inland. The main column under Hannibal, along with the treasure chest and elephants, crossed the Ebro at the town of Edeba and proceeded directly along the coast through Tarraco, Barcino, Gerunda, Emporiae and Illiberis. The separate detachments marched in a way to provide mutual support if needed, and the coastal detachment under Hannibal was also tasked with countering any possible Roman intervention.