Gaugamela: Alexander's Shattering Thrust at the Persian Heart

Alexander the Great of Macedon enjoyed the most successful military career of any general from antiquity. Following the assassination of his father, Philip II, in 336 B.C., Alexander was proclaimed king of Macedon by his nobles. He inherited command of the professional Macedonian army at the age of 20, an army born from the genius of Philip and tempered by warfare against the Greek city-states. Already an experienced battlefield commander at the time of his ascension to the throne, Alexander leveraged his own strategic and tactical brilliance with the established potency of his father's army. The result was an unstoppable juggernaut, led by Alexander through the greater Greek land area and then eastward into the Persian empire.

One battle in particular, the Battle of Gaugamela (331 B.C.), deserves to be singled out as a case-study of decisiveness in warfare, a truly decisive battle. First, however, a brief description of the Macedonian army needs to be articulated in order to set the stage for Gaugamela's narration.

Philip constructed a brand new type of army, something never seen or tried before in ancient Greece. His primary striking force, the phalanx, was a dramatic evolution of the classic phalanx relied upon by the Greek city-states, most notably Athens, Sparta, Thebes, and Corinth. These states packed their infantrymen together into solid, symmetrical blocks of fighting men. These blocks, or phalanxes, operated as a single unit. Each man carried a spear roughly seven to eight feet in length in one hand and a large, round shield in the other. Their shields protected not only themselves from neck to knee, but also the man to the immediate left of the shield bearer. The battlefield effectiveness of the phalanx relied almost entirely upon its weight, momentum, and cohesion. The phalanx maneuvered forward exclusively, required level ground, and was dangerously exposed to flanking attacks. The force needed to carry the phalanx forward was drawn from the rear ranks as these men supported and urged their countrymen forward. It was this one-dimensional tactical unit that Philip manipulated in order to fashion something far more complex and deadly than its predecessor: the piked heavy-infantry phalanx.

Philip equipped his heavy infantrymen with the sarissa, a spear nearly double the length of those used by the Greek city-states. Macedonian infantrymen were obliged to use both hands in order to hold and wield this larger spear but the added distance of reach Macedonian pikemen enjoyed more than compensated for the more cumbersome burden. Lacking a free hand with which to hold a shield, these pikemen used smaller shields which were strapped to their left arms in order to deflect, inter alia, arrows and javelins.  The first few ranks of the Macedonian phalanx held the points of their sarissas forward directing their spear thrusts into the front ranks of the enemy phalanx. In addition, these longer spears enabled more men from the formation to make contact with the enemy. In effect, up to eighty (80) spear tips would confront the front ranks of an enemy phalanx. This advantage of proximate contact saturated the surface area where the two opposing forces met and while the front ranks fought the middle ranks held their sarissas at an angle to deflect arrows and javelins while the rear ranks held their spears straight upwards.

Coupled with the heavy infantry phalanx, the pikemen, Philip employed additional tactical units to complement the wall of spears. He used stone-throwers called peltasts to disrupt and harass his enemies in order to fracture their lines thereby exposing gaps and holes into and through which the pikemen or cavalry could maneuver. And it was the Macedonian cavalry, the Companion Cavalry, which were the envy of the known world of the 4th century B.C.

Together with allied auxiliaries, these three primary arms of the Macedonian battle order provided Philip with far more flexibility than his Greek counterparts. Simply put: Philip crashed his pikemen phalanx into the front lines of the enemy's phalanx thereby pinning them and halting their forward momentum. His phalanx made deadly contact with the enemy before their shorter spears could be used and in greater numbers.  As this initial contest was unfolding, Philip harassed the enemy flanks with his peltasts and readied the cavalry wings of his army for their eventual, decisive attack.

As holes and gaps emerged within the enemy phalanx -- and they invariably did -- Philip thrust his Companion Cavalry into these holes and gaps forcing the entire formation to split and in-so-doing depriving the classic phalanx of its battlefield modus operandi. This 'hammer and anvil' maneuver worked so well that, following the Battle of Chaeronea (338 B.C.), Philip rendered the phalanx of the Greek city-states obsolete. Never again were land battles fought by one-dimensional armies. Instead, the Macedonian evolution forged a new future where separate and distinct units of the same army complemented one another through the performance of singular, tactical acts as part of a more holistic strategy. This weapon was bequeathed to Alexander at the age of 20 after his father was assassinated in 336 B.C.

And yet he did not shrink from the challenge because he had fought in his father's army since he was 16 and eventually led the Companion Cavalry. It was to his credit that Philip's victory at Chaeronea proved so decisive. As the Macedonian line pivoted around its center, Alexander led his Companion Cavalry wing in an arching, wheel-type motion and smashed into the enemy lines -- in this case an alliance of Greek city-states led by Athens and Thebes -- sowing panic and confusion within the fragmented phalanx formation. To disrupt and/or dismantle the solid, closely guarded nature of the phalanx was tantamount to a death sentence. This was so because the individual infantryman -- the hoplite -- drew his fighting strength from his proximity and connection to the other hoplites within the phalanx. The integrity of a phalanx's form was an existential necessity and it was this necessary condition that Philip's multi-faceted army proved so capable of depriving the Greeks of. Standing alone, single hoplites were poorly equipped for battle and easy pray for the type of massive, shock attack Alexander's cavalry was known for.

After the two heavy-infantry units of both armies engaged one another Alexander routinely arrayed his cavalry into a wedge formation. This tactical organization during an attack facilitated the aggravation and exploitation of gaps within the enemy lines. And this specialized formation enjoyed the added benefit of Alexander's leadership and charisma.

Alexander led this shock unit into battle as the first soldier among a group of equals. Raised in the saddle, Macedonian cavalrymen were consummate riders and deadly soldiers. They used the rugged, mountainous terrain of the Macedonian landscape as a learning ground and implemented their skillful precision during battle first for Philip and then under Alexander beginning in 335 B.C.

Upon his ascension, numerous Greek city-states to the south of the Macedonian kingdom rebelled against Alexander hoping to rid themselves of Macedonian overlordship. In response Alexander first invaded Thrace and then marched on the rebellious Greek city-states. This consolidation of power began in 335 B.C. and ended only after Alexander crushed Theban resistance, sacking Thebes and razing the city to the ground. Upon the conclusion of this early success, Alexander embarked upon what we now know to be his lengthy and miraculous invasion of Persia and the far east.

Route of Alexander's conquests. 

After crushing Greek resistance Alexander next invaded the vast Persian empire, an act his father would have likely undertaken had he not been assassinated. In quick succession, Alexander won brilliant victories at the Battle of Grannicus (334 B.C.) and then again at the Battle of Issus (333 B.C.). In addition Alexander laid siege to and eventually sacked a number of cities which were ruled by Persian satraps: Halicarnassus (334 B.C.), Tyre (332 B.C.), and Gaza. These accomplishments set the stage for Alexander's most impressive battlefield performance: the Battle of Gaugamela (331 B.C.).

The Persian King, Darius III, exercised personal control over his armies after the Battle of the Grannicus river. He organized a meticulous plan for the battle on the flat plains of Gaugamela leaving nothing to chance, his two-to-one troop advantage notwithstanding. In fact, the Persians numbered roughly 87,000 to 90,000 troops divided into the following units: Peltasts - 30,000; Cavalry - 40,000; Persian Immortals - 10,000; Bactrian Cavalry - 2,000; Archers - 1,500; Scythed Chariots - 200; War Elephants - 15. Particularly menacing were the Scythed chariots which brandished sharp blades from their wheel-spokes and which specialized in decimating infantry formations. Darius went so far as to level the ground upon which his chariots would charge, effectively creating 'lanes' for an attack.

The Persian line extended miles in each direction and no matter how thin Alexander made his line he could not stretch it far enough to protect his flanks from a Persian envelopment. And so he did what all great commanders do when faced with an insurmountable problem: he approached the problem from another direction and created for himself a tailor-made answer to this conundrum. Instead of deploying his battle-line in a parallel, squared-up orientation vis a v. the Persian line -- an act which would surely guarantee a Persian victory -- Alexander had his army deployed in echelon, or a slanted, oblique formation with his left flank refused. Sounds technical, yes, but this organization can be easily explained.

The Persians outnumbered Alexander's Macedonians by a factor of two (2), that is two Persians for every Macedonian. If Alexander reacted passively by accepting battle on the terms set forth by Darius then his army, the Macedonians, would surely  suffer defeat. And so Alexander took the initiative and built a strategy that exercised his army's strength -- the Companion Cavalry -- in relation to the Persian masses.

He tucked his left wing down and in facing the Persian line at an angle in preparation for Darius' flanking maneuver. This is referred to as refusing one's flank, the weaker flank of one's army. To refuse one's weak flank is to protect it from the enemy's numerical superiority while striking with the other flank. Alexander instructed his trusted lieutenant, Parmenio, to 'wheel back and to the left,' constantly turning to face the Persian attack. So long as this wing of the Macedonian army survived Alexander could administer a sharp cavalry charge into the heart of the Persian army. While Parmenio commanded the refused left flank during the battle, Alexander sent his piked-phalanx forward at an angle to make contact with and pin down the Persian center. These two maneuvers -- refusing his left flank on the one hand and using his phalanx as a holding force on the other -- enabled Alexander to effectively neutralize the Persian advantage of numerical superiority. Alexander's final stratagem was offensive, and decisively so. After all, the justification for arranging one's army in echelon, or in an oblique order, is to stall and hold the enemy's line at one point in order to concentrate one's striking arm at another, local point using a superior force. So how did Alexander do it?

Tune in tomorrow, or today rather, for the dramatic climax to the Battle of Gaugamela...