The Arsenal

The sarissa was the defining weapon of the Macedonian phalanx — an 18-to-21-foot pike made of cornel wood in two sections joined by a bronze sleeve, weighing roughly 15 pounds. Wielded two-handed, it projected 10 feet beyond the front of the phalanx, meaning five or six ranks of pikes overlapped the front man's position. An enemy facing the phalanx met a wall of overlapping points before they could reach the Macedonian soldiers. The sarissa was Philip II's innovation, transforming the Greek phalanx from a single-rank shoving match into a deep formation of pikes. Its weakness was flanks — if the phalanx's flanks were exposed, the long pikes became unwieldy. Alexander's genius was consistently protecting those flanks with the Companion Cavalry.

The Companion Cavalry — the Hetairoi ('Companions') — were Alexander's arm of decision, the hammer that Parmenion's pike phalanx held the enemy in place for. Drawn from the Macedonian and Thessalian nobility, perhaps 1,800–2,000 men at campaign start, they rode without stirrups (stirrups had not yet reached the Mediterranean) but compensated with deep saddles and exceptional horsemanship. Armed with the xyston — a cornel wood lance 10 feet long — and a xiphos short sword, they fought in the wedge formation, which allowed rapid pivoting and penetration of a narrow point. Alexander personally led the Companions into the decisive gap at every major battle — Granicus, Issus, Gaugamela. They were the weapon that decided three empires.

Alexander inherited from Philip II a siege engineering corps whose capabilities were unprecedented in the Greek world. Torsion-powered catapults (using twisted sinew) that could throw 60-pound stones accurately at ranges of 200 yards, arrow-shooting ballistae, siege towers tall enough to overtop city walls, and mobile shelters (tortoises) for workers undermining walls. The Siege of Tyre showcased these capabilities: Alexander mounted his heaviest artillery on specially built ships and pontoon barges, creating the first naval artillery platform in history. The causeway itself required engineering solutions — keeping the mole from being swept away by currents, protecting the workers from Tyrian fireships — that drew on everything Macedonian military engineers knew.

The xyston was the Companion Cavalry's primary weapon — a cornel wood lance of about 10 feet, held two-handed or in the right hand with an underarm grip. Unlike the thrusting spear of hoplite infantry, the xyston was designed for a single high-speed shock pass: the rider aimed the point at the target, used the momentum of the galloping horse to drive it through, and if the xyston broke (as it frequently did) drew the kopis or xiphos short sword for melee. Cornel wood was chosen for its weight, hardness, and flexibility — it absorbed the impact of a lance thrust without shattering as often as ash or pine. Persian cavalry typically used javelins rather than lances, giving Macedonian cavalry an advantage in a direct charge.

The kopis was a forward-curved, single-edged blade about 18 inches long, optimized for a downward chopping slash that could penetrate through helmets and light armor. It was the preferred sidearm of Macedonian cavalry, who needed a weapon they could swing one-handed at a downward angle from horseback. Unlike the straight thrusting xiphos, the kopis concentrated force in the cutting blow. Archaeological finds from Macedonian graves show kopides with ivory and bone handles and elaborate bronze scabbards — these were prestige weapons as well as practical ones, and the finest examples were personal heirlooms. The Macedonian cavalry at Granicus used kopis after their xystons broke; Alexander himself is depicted in battle art with a kopis.

The Persian composite bow — made from layers of horn, sinew, and wood laminated together — was the standard weapon of Persian cavalry and infantry archers and one of the most powerful bows in the ancient world. A skilled archer could reach 300 yards; effective fighting range was 50–150 yards. Persian armies typically opened battle with a coordinated archer volley designed to disrupt enemy formations before cavalry contact. At Issus and Gaugamela, Persian archers inflicted significant casualties on the Macedonian phalanx before Alexander's cavalry charge disrupted their formation. Their weakness was vulnerability once cavalry closed the distance — archers cannot reload and fire a composite bow quickly enough to stop a cavalry charge in its last 100 yards.

Darius III deployed 15 war elephants at Gaugamela — probably acquired from his eastern satrapies — but they played little role in the battle. King Porus fielded 200 at the Hydaspes, using them effectively to anchor his infantry flanks and deny Alexander's cavalry the approach lanes they needed. Each elephant was the size of a tank and capable of crushing a man flat or lifting a soldier with its trunk. Alexander's response evolved over the battle: infantry opened lanes for the elephants to pass harmlessly, while archers and javelin men harassed the elephants' mahouts (drivers). When a mahout was killed or the elephant was panicked by wounds, it became as dangerous to its own side as the enemy. After the Hydaspes, Alexander incorporated captured Indian elephants into his own army.

The Hypaspists — 'shield-bearers' — were the elite infantry unit that bridged the gap between the pike phalanx and the Companion Cavalry. Three battalions of 1,000 men each, they carried the traditional hoplite round shield and shorter spear rather than the sarissa, which gave them agility the phalanx lacked. They fought beside Alexander on his right, connecting the cavalry's maneuver with the phalanx's solidity. At the Persian Gates night march over snow-covered mountains, it was the Hypaspists who led the approach. At Tyre, they were the assault infantry who stormed the breach. At the Sogdian Rock, their volunteers climbed the cliff face. They were also sometimes called the Agema — the royal guard battalion.

Darius III deployed 200 scythed chariots at Gaugamela — vehicles with long curved blades mounted on the axles designed to sweep through infantry formations at speed. He had even leveled the ground at Gaugamela specifically for them. They were a complete failure. Alexander had trained his soldiers to open lanes when chariots approached, letting them pass through harmlessly; the drivers were shot down from the flanks; the horses were turned by noise and missiles. Not a single chariot reached the Macedonian phalanx effectively. The scythed chariot was a weapon of an earlier era, designed to fight undisciplined Near Eastern levies, not trained Macedonian professionals who had been specifically trained to counter them.

One of the most uncomfortable facts of Alexander's campaign was that some of the fiercest resistance came from Greek mercenaries in Persian pay. At the Granicus, it was the Greek mercenary infantry who recommended the effective defensive position that Persian cavalry overruled; when captured, Alexander enslaved them rather than free them, on the grounds that fighting against fellow Greeks was treasonous. At Issus, Persian Greek mercenaries formed the core that held longest. Memnon of Rhodes — the most dangerous Persian commander — was himself a Greek. The 'liberation of Greece from Persia' framing was complicated by the large number of Greeks who had chosen Persian employ. After Gaugamela, most remaining Greek mercenaries in Persian service defected or dispersed.