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A powerful army stood poised to cross the Ebro River into northern Spain, comprising soldiers from many peoples and cultures. Yet heterogeneous as the force was, most all of them were veterans of two decades of continuous warfare. It was a cohesive army built for speed and shock, and it answered to one man and one will — Hannibal of Carthage. Swift light cavalry from the desert plains of Numidia screened the main body from curious or hostile eyes. Past this barrier the army stretched for miles: massed squadrons of Iberian cavalry and infantry; mercenary Balearic Islanders, trained from childhood in the art of the sling; archers; javelin men from the tribes of North Africa; mighty elephants plodding forward like mobile watchtowers; veteran Libyan spearmen — more than 80,000 men all told.

Hannibal Barca of Carthage had brought this army to the banks of the Ebro in a fateful year, 218 bc. Ten years earlier, the Senate and people of Rome had forbidden the Carthaginians to cross that river on pain of war. Now nothing could please Hannibal more. The young general was resolved not only to cross the Ebro but also to conduct an epic march across the Pyrenees, on through Gaul, over the Alps and into Italy to threaten Rome itself.

The Romans later believed that Hannibal’s father, Hamilcar Barca, had bequeathed this plan to invade Italy to his son. That great general waged a masterful guerrilla campaign against the legions of Rome in western Sicily during the final seven years of the First Punic War. Undefeated on land, Hamilcar had been forced by a naval defeat to surrender Sicily to Rome in 241 bc. But the end of that war brought no respite for Carthage, which was soon threatened by a bloody mercenary rebellion. Hamilcar ultimately defeated the rebels in 238, but Rome seized the opportunity to annex Sardinia and Corsica. That act of naked aggression, the Rape of Sardinia as the Carthaginians called it, convinced Hamilcar that his home city would never know peace as long as Roman power remained unchecked.

Once the rebels were crushed, Hamilcar embarked on a new expedition to Iberia to carve out an empire that would replace the lost resources of Sicily and Sardinia. Before leaving Carthage, he brought his 9-year-old son Hannibal to a temple to vow ‘never to be a friend of Rome.’ Hamilcar campaigned in Iberia for nine years, until he was killed in battle in 229 bc. The Iberian command passed to his son-in-law, Hasdrubal the Splendid, but it was Hasdrubal whom the Romans had forced in 228 bc to sign the treaty pledging never to cross the Ebro under arms. Hasdrubal continued the expansion of the Barcid empire in Iberia for eight more years until he was felled by an assassin’s blade in 221. The Carthaginian army then acclaimed Hannibal, although he was only 25 years old, as its new commander. So it fell to Hannibal, with his younger brothers Hasdrubal and Mago, to carry out their father’s plan.

Hannibal wasted no time. In two years of hard campaigning he consolidated the Carthaginian hold on southern Iberia and perfected his army. A dispute with the city of Saguntum, allied with Rome but south of the Ebro, provided the pretext he needed to provoke a new war. In 219 bc he laid siege to Saguntum, and after eight months it fell. Rome sent ambassadors to Carthage to demand restitution and Hannibal’s surrender. When the Carthaginian council refused, the Roman diplomats offered a challenge of war — and the Carthaginians accepted. The Second Punic War, or the Hannibalic War, had begun.

In Iberia, Hannibal sent his army into winter quarters and released his Iberian contingents for a final home leave before commencing the great march against Rome. Spies and ambassadors were sent ahead to reconnoiter the route and negotiate with tribal leaders. Gold and silver helped pave the way. Key to Hannibal’s plan was an anticipated alliance with the Boii and Insubres of the Po River valley. These Celtic tribes chafed at their recent subjugation by Rome and eagerly accepted an alliance that promised revenge and freedom. For Hannibal, they offered a base in Northern Italy and manpower.

Hannibal mobilized three armies for his war of retribution. To defend against anticipated Roman invasions, he brought African conscripts to Iberia while dispatching 13,850 Iberian foot soldiers, 1,200 horsemen and 870 Balearic slingers for the defense of Africa. An additional 4,000 infantry garrisoned Carthage, along with the home fleet of about 100 warships. Hannibal designated his brother Hasdrubal to hold Iberia in his absence and provided him with the following forces: 11,850 Libyan spearmen, 500 Balearic slingers, 300 Ligurian infantry, 1,800 Numidian light cavalry, 450 Libyan heavy cavalry, 300 Iberian horsemen, 21 war elephants and 57 warships.

Hannibal’s army in Iberia reportedly totaled 90,000 infantry and 12,000 cavalry, although those figures most probably included Hasdrubal’s forces as well as his own. The expeditionary force would still number as many as 75,000 foot soldiers and 9,000 horsemen. Hannibal departed New Carthage (Cartagena, Spain) in late May, marching 290 miles through friendly territory to arrive at the Ebro by late June. Accompanying him were Mago, his youngest brother; Maharbal, his deputy; Hasdrubal, the quartermaster general; and Hanno, son of Bomilcar. That group of generals would prove to be one of history’s most talented and capable command teams.

Unlike with the Barcid invasion scheme, which had hatched over two generations, Rome hurriedly developed war plans in the crisis atmosphere engendered by the fall of Saguntum in 218 bc. Rome mobilized 64,000 infantry and 6,200 cavalry for the coming year. The Senate planned an offensive two-front war against Carthage. The two consuls elected for that year (who were both chief magistrates and generals) would each lead an invasion.

Publius Cornelius Scipio was assigned two legions (of 4,000 foot and 300 horse each), with 14,000 allied Italian infantry, 1,600 cavalry and 60 warships to do battle with Hannibal in Iberia. The Senate dispatched his colleague, Tiberius Sempronius Longus, to Sicily with a larger force of two legions, 16,000 allied Italian foot, 1,800 cavalry and 172 warships to prepare for invading Carthage, in Africa. Two additional legions with 10,000 allied foot soldiers and 1,000 cavalry were sent to Cisalpine Gaul to overawe the restless Celts.

By the time Hannibal’s army crossed the Ebro, the treaty violation it represented was of little consequence, as Carthage and Rome were already at war. Hannibal conducted a lightning campaign to conquer northern Iberia. Hard fighting subdued four major tribes. The coastal cities were bypassed rather than besieged — Hannibal needed to cross the Alps before winter.

He had expected to meet a Roman invasion army in northern Iberia, but none appeared by late summer. Hannibal decided to press on across the Pyrenees in August, having covered 180 miles since crossing the Ebro. He garrisoned the newly won region with a detachment of 11,000 troops. At the Pyrenees, he released another 11,000 Iberian troops who displayed reluctance to leave their homeland. Hannibal reportedly entered Gaul with 50,000 foot soldiers and 9,000 horsemen.Scipio had indeed hoped to be in Iberia by the summer. In anticipation of Hannibal’s arrival, however, the Boii and Insubres tribes rose in revolt and ambushed the Roman garrison army. The Senate ordered Scipio to dispatch one of his legions, along with 5,000 allies, to relieve the beleaguered force. His invasion had to wait.

Meanwhile, the Carthaginian advance into western Gaul had excited alarm and hostility among the indigenous Celtic tribes. Hannibal arranged a meeting with the Celtic chieftains, and after plying them with gifts, convinced them to allow his army to pass through their territory unmolested. Thereafter, the march from the Pyrenees to the Rhône River, another 180 miles, proceeded smoothly. Arriving at the Rhône in September, Hannibal’s army numbered 38,000 infantry, 8,000 cavalry and 37 elephants.

The Carthaginian army reached a point on the Rhône four days’ march from the sea. The Celtic tribe inhabiting the Rhône Valley, the Volcae, massed on the eastern shore to resist the crossing. Hannibal ordered his men to purchase all available canoes and craft from the Celts living on the west bank, and set about constructing even more boats.

As the multitude of hostile Volcae grew on the far bank, Hannibal realized that a direct assault would likely end in disaster. Therefore, on the third night after reaching the river, he secretly dispatched a detachment of his army, under the command of Hanno, led by native guides on a 25-mile forced march upriver to a suitable crossing point. Gathering a few boats, the column rapidly crossed the river. Many of the Iberians swam across, assisted by inflating the leather bags in which they carried their gear. Hanno pitched a camp on the far shore and allowed his men a day of rest.

Meanwhile, Hannibal openly prepared his army for an assault river crossing, fixing the attention of the Volcae Celts. On the morning of the fifth day, he observed the prearranged smoke signal he had been awaiting from Hanno and sent his men into the water. The largest boats were stationed upstream, to break the force of the current. The cavalry horses swam behind the boats, troopers in the stern of each craft holding their reins. Infantry crossed in canoes and other small craft.

Even with the large number of boats Hannibal had collected, only a fraction of his army could cross in the first wave. As the armada surged toward the opposite shore, the Volcae swarmed out of their camp to occupy the beach. From one bank the Carthaginian army shouted encouragement to their comrades in the water; from the other the wild Celts issued their challenge to battle.

Just then Hanno’s detachment stormed into the rear of the Volcae host while a few of his units set fire to the Volcae camp. A few of the Volcae rushed back to save their camp, while the remainder remained focused on repelling the amphibious assault. Hannibal brought his first wave ashore and launched a vigorous attack. The Volcae, under attack from two directions, broke and scattered. Hannibal quickly brought most of his army across the river, save for a rear guard and the elephants. That evening, however, his scouts brought unexpected news — a Roman army had arrived at the mouth of the Rhône. Hannibal dispatched a squadron of 500 Numidian cavalry to reconnoiter the enemy force.

After detaching a legion to suppress the Boii and Insubres in Cisalpine Gaul, Scipio had hurriedly conducted another levy when he received the alarming news that Hannibal had not only crossed the Ebro but was advancing through the Pyrenees. Scipio decided to sail to the friendly Greek city of Massilia (modern Marseille), at the mouth of the Rhône, which he could use as a secure base to campaign against Hannibal in Gaul. Five days at sea brought his 24,200 men and 60 ships to Massilia. There, Scipio was shocked to learn that Hannibal’s army was just a few days’ march upriver. He had never expected the Carthaginians to march so far so quickly. Scipio sent a picked force of 300 cavalry, reinforced with Celtic mercenary horsemen, to scout out the reported enemy.

Getting their elephants across the Rhône posed special problems for the Carthaginians. The animals refused to board boats or small rafts for the crossing. Hannibal directed his pioneers to construct a number of large rafts, 25 feet square. These were lashed together in pairs, and eight pairs were attached to the bank, forming a pier 50 feet wide and extending 200 feet into the river. Two additional rafts were attached to this pier and connected with tow-lines to boats. The rest of the elephants had refused to venture onto boats in the river, so the pier was disguised as dry land, covered with dirt. The elephants were led by two compliant females across the pier and onto the raft. Then the rafts were cut free and towed across the river. The elephants panicked at first but eventually crowded toward the center of the raft and made the crossing safely. The process was repeated a number of times, and though a few of the frightened elephants fell into the water, even they managed to swim across.

Meanwhile, the reconnaissance forces dispatched by Hannibal and Scipio collided. A fierce battle ensued, which the Romans and their Celtic allies won, killing more than 200 Numidians while losing 160 of their own men. The Romans rode on to observe Hannibal’s camp, then hurried back the 50 miles to Scipio’s camp to issue a full report. Without hesitation, Scipio put his army in battle order and advanced to engage the Carthaginian host.

Hannibal briefly considered offering battle to Scipio’s army, but the arrival of Magilus, a chief of the Boii, convinced him to make all haste to cross the Alps. Magilus assured Hannibal that the Boii would rise up in full strength upon his arrival and would minimize his difficulties in crossing the Alps. Hannibal arranged a mass assembly of his army so that Magilus and his delegation could address the troops and encourage them with promises of aid and support in Italy. Hannibal then started his infantry marching north while his cavalry screened the rear.

Scipio’s army arrived at the Carthaginian crossing site to find an empty camp. Hannibal’s rear guard had departed three days earlier. Scipio was not keen to pursue the Carthaginians into the trackless wilderness, so he marched his army back to the coast. He now had to make some hard decisions. The Senate had ordered him to invade Iberia and engage Hannibal, but Hannibal was well on his way to Italy.

Scipio reached a strategic decision that proved to be one of the most important of the war. He dispatched the bulk of his army under the command of his older brother, Gnaeus Cornelius Scipio, to carry on with the invasion of Iberia. Publius Scipio himself hastened back to Italy. He planned to take command of the Roman troops already in Cisalpine Gaul. With that army, he would engage Hannibal when, or if, he emerged from the mountains.

Meanwhile, Hannibal pressed on toward the Alps and his destiny. After marching four days, the army reached the confluence of the Rhône and Iskaras (either the modern Isere or Aygues) rivers. This area was known as the ‘island,’ hemmed in on two sides by rivers and on the third by mountains. There, Hannibal intervened in a local tribal succession dispute between two brothers. With Hannibal’s aid the elder brother, Brancus, became chief. In gratitude, Brancus provided the Carthaginian army with rations, cold-weather gear, guides and escorts. The next 10 days’ marching was uneventful. It had been 160 miles from the Rhône crossing to where the Carthaginians reached the Alps in mid-October. They now entered the territory of the fierce and powerful Allobroges Celts, who were vehemently opposed to allowing any foreign army into their lands.

The Allobroges occupied the high ground dominating the trail into the mountains. Hannibal halted his army and sent out his scouts. They discovered that the Allobroges only manned their outposts during daylight, returning to their villages each night. After dark, Hannibal dispatched light infantry to occupy the key positions. At dawn, as his army advanced into the ravine, the hostile Celts, scrambling to get into position, were dismayed to find Carthaginian infantry already occupying the high ground. The Allobroges hesitated, unsure of what course to follow. Nevertheless, when they observed the long column, strung out and vulnerable, they couldn’t resist launching an attack.

The Carthaginian column was thrown into turmoil, with many of the beasts of burden stampeding. Hannibal’s light troops counterattacked, routing the Allobroges below them, but that only added to the confusion. Both sides suffered heavy losses as men and beasts fell from precipitous cliffs or were trampled or crushed by falling rocks. Hannibal’s light infantry pursued the broken Allobroges back to their villages, capturing food and supplies to make good some of the losses.

Hannibal rested his army for one day and restored order. The Carthaginians were able to march on unmolested for the next three days. Then the elders of another mountain tribe came out to meet Hannibal with gifts and promises of aid. The general remained suspicious, but some of his fears were allayed when the Celts provided him food, hostages and guides to lead them through the next portion of the mountains. At first all seemed well, but the treacherous guides led the Carthaginians into a steep ravine where their warriors waited in ambush. Hannibal, having foreseen that possibility, had placed all his cavalry and baggage at the head of the column, while his infantry brought up the rear. When the ambush was sprung, the cavalry and baggage column got through with few losses. The infantry had some hard fighting, but it was the terrain itself, and the boulders rolled down from above, that resulted in the most casualties. Hannibal eventually brought his army through the ambush.

This proved to be the last major attack the Carthaginians faced, as the higher mountains were sparsely populated. Yet small bands continued to beleaguer his army with occasional raids and skirmishes. The elephants proved their worth during this leg of the march, as the tribal warriors feared to even approach the strange beasts wherever they were stationed along the column. From here on, however, nature itself became the enemy. Soldiers born and bred in the sunny lands of Africa and southern Iberia suffered horribly from the bitter cold, short rations and thinning air — and then the snow began to fall.

On the ninth day since entering the Alps, the army reached the summit and Hannibal set up a camp to rest his weary men for two days. Stragglers and pack animals continued to wander into this camp, following the column’s tracks. The snow was falling heavily, and the army was in low spirits. To restore courage and resolve in his men, Hannibal brought them forward to a point from which they could see the lush green plains of the Po Valley in Italy in the distance.

Though the going was now downhill, it did not become any easier for Hannibal’s tired, hungry troops. The slopes were actually steeper on the Italian side of the pass, and fresh-fallen snow on top of compacted ice made for extremely treacherous footing. Many exhausted soldiers fell and slid to the side of the trail. Some were too tired to get up at once, and many were never to rise again. Adding to the difficulty, a large portion of the trail had been blocked by a landslide. The Carthaginian scouts could discover no detour. Hannibal was forced to send his sappers to work. They cut through a great boulder, first heated with bonfires and then doused with wine and vinegar. A narrow trail was cleared in a day, and the horses and mules were rushed across to reach fodder below the tree line before they succumbed to starvation. Two more days of labor were required to widen the path enough for the elephants, and then the rest of the infantry followed.

The Carthaginians had covered another 140 miles on this last leg of the march through the Alps, bringing the total journey to nearly 1,000 miles. They finally reached Italy in late October, five months after departing New Carthage and 15 days after entering the Alps. Hannibal now took stock of his army. A mere 20,000 infantry and 6,000 cavalry remained, but these were the hardiest of men, veterans of brutal conflict with man and nature.

In Rome, the Senate was stunned. All had expected to fight this war in Iberia and Africa, but now a Carthaginian army was in Italy. Hannibal had seized the initiative, and Rome’s leadership, unhinged by this bolt from the blue, could only react. They canceled the invasion of Africa and ordered Consul Sempronius to bring his army from Sicily as quickly as possible to reinforce Scipio.

While Hannibal’s army was approaching the Alps, Scipio had rushed to Cisalpine Gaul to take command of the two legions and allied troops stationed there. Scipio knew he was outnumbered but reasoned that Hannibal’s army must be in miserable condition after crossing the mountains. He also knew that any hesitation to engage the Carthaginians would lead the Celtic tribes into widespread defections, so he hastened toward Hannibal’s reported location. Near the Ticinus River, Scipio led out his 2,000 cavalry and 4,000 light infantry, seeking the enemy.

After a brief rest, the Carthaginians had recovered enough stamina to march once more. Before moving against the Romans, Hannibal staged a display of gladiatorial combat. He brought Celtic prisoners, taken in the Alps, before the army in chains. Hannibal asked the prisoners who would be willing to engage their fellow prisoners in mortal combat, the victor winning freedom and rich prizes, the loser finding an end to slavery in death. All the prisoners excitedly begged for the chance. A few pairs were chosen by lot and fought to the death before the assembled army.

Then Hannibal addressed his men, explaining that this display was a vivid representation of their own situation. They too were offered the same choice: victory or death in battle. Or did anyone think it would be possible to retreat the way they had come? Conquer or die, and the prize was the wealth of Italy laid out before them. The Carthaginians clamored to be led into battle, and Hannibal obliged them.

Hannibal preceded the column with his 6,000 cavalry and met Scipio’s force at the Ticinus. The Carthaginian cavalry was not in the best condition, but it still proved more than a match for Scipio’s conscript horsemen and light infantry. The Romans were routed, and Scipio himself was wounded and nearly captured. Only a heroic charge led by his 17-year-old son and namesake saved the wounded consul. That same youth would one day defeat Hannibal at Zama and earn the title ‘Africanus.’

Scipio fell back to high ground on the Trebbia River, awaiting the arrival of his colleague. Hannibal allowed Sempronius’ army to link up with Scipio’s on the Trebbia. He needed a decisive victory quickly, as it was already December and well past the usual campaigning season. For his part, Sempronius sought a glorious victory before his year as consul came to an end. Hannibal chose the time and the place for the coming battle. He first placed his brother Mago with a detachment in ambush. His soldiers ate an early breakfast, then warmed themselves before fires and rubbed down their limbs with heated oil. Hannibal sent out his Numidian cavalry to provoke the Romans, and Sempronius ordered his entire army out of camp — without breakfast. The Numidians led them back through the freezing waters of the Trebbia River and onto Hannibal’s chosen ground.

Hannibal’s army had grown to 28,000 foot soldiers and 10,000 horsemen as Celtic recruits streamed in. Sempronius’ army comprised 36,000 infantry and 4,000 cavalry. The Roman legionaries, wet, cold and hungry, launched a frontal assault. Hannibal’s cavalry, spearheaded by elephants, quickly routed the outnumbered Roman horsemen, then flanked the Roman infantry while Mago’s picked force struck them in the rear. Hemmed in on all sides, the Romans fought on. Some 10,000 legionaries cut their way through the Carthaginian center and reached safety. Nearly all the remaining Romans were killed or captured. Hannibal had achieved the decisive victory he sought on the Trebbia, the culmination of his great march.Over the next two years Hannibal’s army would blaze a historic path of one glorious victory after another over the legions of Rome. Three consuls and a master of horse were humbled and tens of thousands of Romans were slain or captured at the Battles of Lake Trasimene, Geronium and Hannibal’s ultimate tactical masterpiece, Cannae.

Although the Carthaginians would ultimately lose the Second Punic War, for 16 years Hannibal’s army in Italy seemed invincible. His crossing of the Alps, which so unnerved the Romans at the start of the war, would also capture the imagination of generations to come. Hannibal had challenged not only Rome but nature itself, and even the Alps could not defeat his will.


This article was written by Daniel A. Fournie and originally published in the March/April 2005 issue of Military History magazine. For more great articles be sure to subscribe to Military History magazine today!