If Alexander the Great had fought the ancient Romans, who would have won?

Alexander’s empire-building began in 334 BCE when he set out to conquer the Persian Empire, the largest and most powerful empire of its time.

Over the next decade, Alexander’s campaigns swept through Asia Minor, Egypt, and deep into Persia, extending as far as the Indus Valley.

His conquests brought him to Babylon, the heart of the Persian Empire, and established Macedonian rule over vast territories.

This expansion created a sprawling empire that stretched from Greece to India, linking the West and the East through a series of campaigns that overthrew established powers.

By the time of his death in 323 BCE, Alexander had carved out the largest empire the world had seen, yet it was held together more by his presence than by any lasting infrastructure. 

In contrast, Rome’s expansion began more slowly, but with greater endurance. The Roman Republic began its rise in the 4th century BCE, conquering neighboring cities and regions within Italy.

By 264 BCE, Rome had become the dominant power in the Italian peninsula and turned its attention to the wider Mediterranean.

The Punic Wars against Carthage, starting in 264 BCE, was the beginning of Rome’s transformation into a Mediterranean empire, with key victories in Sicily, Spain, and North Africa.

Unlike Alexander’s rapid campaigns, Rome expanded through a series of wars and treaties over centuries.

By 146 BCE, after the destruction of Carthage and the defeat of the Greek city-states, Rome had established itself as the dominant power in the Mediterranean world. 

The Macedonian phalanx, which had been perfected by Alexander’s father, Philip II, was a disciplined wall of men and spears.

Each soldier, or phalangite as they were known, carried a sarissa, a pike stretching between 16 and 20 feet in length.

This formidable weapon allowed them to strike at enemies long before they could get close enough to respond.

In addition, the soldiers stood in tight formation, sometimes as many as sixteen ranks deep, with the front lines holding their sarissas parallel to the ground, which created an impenetrable forest of spears.

Ultimately, the strength of the phalanx lay in its solid front line and the sheer weight of its advance.

To operate at its best, it required flat, open terrain, where its lines could remain unbroken and maintain momentum.

However, its rigid formation made it vulnerable to attacks on the flanks and rear, especially if its cohesion faltered. 

In contrast, the Roman legion was far more flexible. A typical Roman legion consisted of about 4,800 men, divided into cohorts of around 480 soldiers.

These cohorts were further broken into centuries, units of about 80 men led by centurions.

Roman soldiers carried short swords, known as gladii, which were ideal for close-quarters combat, along with large rectangular shields that provided excellent protection.

Closest in time to Alexander's reign, the Romans often used the manipular formation, which allowed for greater mobility and adaptability on the battlefield.

Unlike the phalanx, the legion could fight effectively in varied terrain. It could easily rotate exhausted soldiers out of the front lines and replace them with fresh troops.

This ability to maintain stamina during prolonged engagements gave the Roman army a brutal edge in wearing down their enemies. 

While the Macedonian phalanx relied on overwhelming power and unity, the Roman legion emphasized versatility and endurance.

The phalanx excelled in direct, head-on confrontations, crushing enemies with its seemingly impenetrable front, but it could not quickly pivot or respond to sudden changes in the battle.

The Roman legion, though less imposing in appearance, excelled at outmaneuvering opponents.

Its soldiers were trained to operate as smaller, independent units, capable of adapting to shifting conditions on the battlefield.

In a prolonged engagement, this flexibility often proved deadly for more rigid formations like the phalanx. 

Alexander the Great famously led from the front and apparently inspired his men with his fearless presence on the battlefield.

In a number of key battles, he even charged into the thick of combat, often risking his life alongside his soldiers.

This charismatic style of leadership was thought to have created a deeply personal bond between Alexander and his army, the Hetairoi and the Companion Cavalry in particular.

His soldiers knew their king fought with them, which increased their morale and inspired them to greater feats of bravery.

For example, his victories at Issus and Gaugamela were both tactical triumphs and triumphs of inspiration, as his army often fought harder because of their king’s presence.

However, this reliance on one man’s command also made his forces vulnerable when he was injured or away from the battlefield. 

In contrast, Roman generals, such as Scipio Africanus and Julius Caesar, commanded through a rigid and structured system that ensured continuity and discipline.

The Roman army relied on a hierarchy of officers, from centurions to legates, who executed strategies with predetermined precision.

While each general could devise innovative strategies, the army’s strength came from the collective efforts of its officers.

Also, individual Roman soldiers fought not for one man but for the glory of Rome, for the Senate, and for their legions.

This structured approach ensured that even if a single commander fell, the army continued to function as a cohesive unit.

Scipio’s victories in the Second Punic War, particularly at the Battle of Zama, demonstrated this system’s long-term effectiveness.

Caesar, while known for his personal bravery, also worked within this framework, combining his strategic mind with the discipline of his legions to secure victories like the famous siege at Alesia. 

Macedonian naval power during Alexander’s reign was relatively limited compared to the scale of his land campaigns.

Although Alexander did assemble a fleet, it was not a central focus of his military strategy.

His navy, which would have been largely composed of ships inherited from the Greek city-states, played a supporting role in the conquest of coastal regions like Tyre in 332 BCE.

At its height, Alexander’s navy consisted of around 200 warships, partly triremes, which were effective for controlling the Aegean Sea and parts of the eastern Mediterranean.

However, naval warfare was not a strength of the Macedonian military. Alexander relied heavily on his army’s ability to move quickly over land, securing supply routes through conquest rather than naval dominance.

While his fleet succeeded in smaller operations, it lacked the ability to project power over long distances or across the wider Mediterranean. 

In stark contrast, the Roman Republic built one of the most powerful and efficient navies in the ancient world.

By the end of the First Punic War in 241 BCE, Rome had constructed a fleet of over 330 ships, including large quinqueremes, which could carry more soldiers and equipment than the smaller Macedonian triremes.

Roman naval victories, especially over Carthage, demonstrated the Republic’s growing expertise in maritime warfare.

The use of the corvus, a boarding device that allowed Roman soldiers to storm enemy ships, turned naval battles into infantry engagements, a tactic suited to Rome’s military strengths.

Roman naval logistics were also highly developed, allowing the transportation of large armies across the Mediterranean.

By the 2nd century BCE, Rome had established permanent naval bases in strategic locations such as Sicily and Spain, ensuring control over key sea routes and enhancing its ability to project military power across the Mediterranean. 

Logistics also played a crucial role in the success of both empires. Alexander’s logistical system relied on speed and mobility, with his armies covering vast distances in short periods.

His supply lines were often improvised, relying on local resources and foraging to sustain the troops.

After capturing Babylon, Alexander demonstrated remarkable logistical skill by resupplying his army through the Persian royal road system, which linked major cities.

However, this system had its limits. When advancing into more remote regions, such as his campaign in India, logistical challenges became severe.

His army struggled to maintain supplies, especially during long sieges or in harsh environments. 

Roman logistics, by comparison, were far more organized and methodical. The Roman legions moved with a steady supply of food, weapons, and reinforcements, which they carried in a well-planned network of supply lines.

Roman engineers constructed roads that spanned the empire, allowing for the rapid movement of troops and supplies.

During campaigns, the Roman army often carried 15 days' worth of rations, and large depots were established along the way to keep the soldiers well-fed and equipped.

Rome’s mastery of logistics ensured that its armies could operate far from home for extended periods without suffering from the same supply issues that Alexander’s forces faced in distant territories. 

If Alexander had lived to confront Rome, the timing of such a conflict would have greatly influenced the outcome.

At the time of Alexander’s death in 323 BCE, Rome was still in the early stages of its expansion, having recently secured control of Italy.

While the Roman Republic showed great promise, it lacked the vast resources and military experience that Alexander’s empire commanded.

Alexander’s genius lay in his ability to adapt to any situation on the battlefield, outmaneuvering enemies with bold strategies and using speed to his advantage.

The Roman army of this period, while disciplined and determined, may have struggled to match his tactical brilliance in a direct confrontation.

Alexander’s victories over the larger and more established Persian Empire suggest that his forces, with their aggressive cavalry and powerful phalanx, could have overwhelmed the early Roman legions in open battle. 

However, had Alexander risen later, during the period of Rome’s Mediterranean dominance, a confrontation would have been far more balanced.

The Roman Republic, by the 2nd century BCE, controlled a vast array of resources, including the fertile lands of North Africa and the rich cities of Greece.

Its ability to draw on a wide network of allied states and provinces would have posed a significant challenge to Alexander’s centralized empire.

It would have been Rome’s ability to endure setbacks and adapt over time would have made them a challenging opponent for even the most brilliant commander.

Unlike the kingdoms that Alexander conquered, Rome’s strength came from the resilience of its institutions and the collective discipline of its citizens.

Even if Alexander had won a series of early battles, the Roman Republic was known for recovering from defeat and learning from its mistakes.

The Punic Wars, fought later against Carthage, demonstrated this capacity, as Rome rebounded from devastating losses like those at Cannae to eventually defeat its rivals.

If Alexander had pushed deep into Roman territory, he would have faced a society willing to sacrifice everything to defend itself. 

Also, in a hypothetical clash between Alexander and the Romans, terrain would have played a decisive role.

On flat, open ground, Alexander’s phalanx would likely dominate, with its long pikes creating an almost impenetrable front.

His cavalry, particularly the Companions, would exploit any gaps in the Roman lines, using the open space to execute flanking maneuvers.

However, in mountainous or uneven terrain, the Roman legions would gain the upper hand.

Their ability to fight in smaller, more mobile units allowed them to maintain discipline and cohesion, even in difficult conditions. 

In the end, the outcome of such a war would likely have depended on timing and the nature of the conflict.

In a short, direct campaign, Alexander’s genius and aggressive tactics may have brought him victory, allowing him to march through Italy as he had done through Persia.

But if Rome had managed to survive the initial onslaught and prolong the war, its resilience and disciplined military structure could have worn down Alexander’s forces.

While Alexander was one of history’s greatest military minds, Rome’s ability to endure and evolve may have ultimately posed a formidable challenge, even to him.