Battle of the Persian Gate

The Battle of the Persian Gate was fought at the Persian Gate northeast of today's Yasuj in Iran between a Persian army led by Ariobarzanes and the invading Macedonian army of Alexander the Great. In the winter of 330 BC, Ariobarzanes led a last stand of the Persian forces against Alexander's forces and successfully held the Macedonian army at bay for 30 days. But, ultimately, Ariobarzanes could not stop Alexander from invading Persepolis and conquering the Persian Empire.

Background
The Persian Empire suffered a series of defeats against the Macedonian forces at Issus and Gaugamela, and by the end of 331 B.C. Alexander had advanced to Babylon and Susa. A Royal Road connected Susa (the first Iranian capital city in Elam) with the more eastern capitals of Persepolis and Pasargadae in Persis, and was the natural venue for Alexander's continued campaign. Meanwhile, King Darius was building a new army at Ecbatana (western province of Hamadan in present-day Iran). Ariobarzanes was charged with preventing the Macedonian advance into Persis, and to this effect he relied heavily on the terrain Alexander needed to pass through. There were only a few possible routes through the Zagros Mountains, all of which were made more hazardous by winter's onset.

After the conquest of Susa, Alexander split the Macedonian army into two parts. Alexander's general, Parmenion, took one half along the Royal Road, and Alexander himself took the route towards Persis. Passing into Persis required traversing the Persian Gates, a narrow mountain pass that lent itself easily to ambush.

The motives
During his advance, Alexander subdued the Uxians, a local hill-tribe, and believed that the surrounding Persian tribes would flee as a result. As he passed into the Persian Gates he met with no resistance, confirming his earlier suspicions. Believing that he would not encounter any more enemy forces during his march, Alexander neglected to send scouts ahead of his vanguard, and thus walked into Ariobarzanes' ambush.

The valley preceding the Persian Gate, called the Tang'e Meyran, is initially very wide, allowing the Macedonian army to enter the mountains at full march. Ariobarzanes occupied a position near the modern-day village of Cheshmeh Chenar. The road curves to the southeast (to face the rising sun) and narrows considerably at that point, making the terrain particularly treacherous. (And thus well suited for Ariobarzanes's purposes.) According to historian Arrian, Ariobarzanes had a force of 700 men who faced a much larger Macedonian force of 10,000. "Arrian's 700 can thus be interpreted as indicating the total strength of Ariobarzanes. Against them Alexander led an army of well over 10,000 men, for having sent Parmenion with the baggage train and heavier-armed troops down the carriage road, he himself took the Macedonian infantry, the lancers and archers through the mountainous track (Arrian, Anabasis 3.18.1; Curtius 5.3.16f.; Diodorus 17.68.1; Stein, op. cit., pp. 19f.)"

The battle
The Persian Gate was only a couple of meters wide at the point of ambush. Once the Macedonian army had advanced sufficiently into the narrow pass, the Persians rained down boulders on them from the northern slopes. From the southern slope, Persian archers and catapults launched their projectiles. Alexander's army initially suffered heavy casualties, losing entire platoons at a time. The Macedonians attempted to withdraw, but the terrain and their still-advancing rear guard made an orderly retreat impossible.

Ariobarzanes had some reason to believe that success here could change the course of the war. Preventing Alexander's passage through the Persian Gates would force the Macedonian army to use other routes to invade Persia proper, all of which would allow Darius more time to field another army, and possibly stop the Macedonian invasion altogether.

Many historians regard the Battle of the Persian Gate as the most serious challenge to Alexander's conquest of Persia.

Aftermath
Ariobarzanes held the pass for a month, but Alexander succeeded in encircling the Persian army in a pincer attack with Philotas and broke through the Persian defenses. Accounts of how he did so vary widely. Curtius and Arrian both report that prisoners of war led Alexander through the mountains to the rear of the Persian position, while a token force remained in the Macedonian camp under the command of Craterus.
 * "[The Persians]...Fought a memorable fight... Unarmed as they were, they seized the armed men in their embrace, and dragging them down to the ground... Stabbed most of them with their own weapons."

Diodorus and Plutarch generally concur with this assessment, although their numbers vary widely. Modern historians W. Heckel and Stein also lend credence to this argument. Although precise figures are unavailable, historians generally agree that this engagement cost Alexander his greatest losses during his campaign to conquer Persia.

According to some accounts, Ariobarzanes, and his surviving companions were trapped, but rather than surrender, they charged straight into the Macedonian lines. One account states that Ariobarzanes was killed in the last charge while another version by Arrian reports that Ariobarzanes escaped to the north where he finally surrendered to Alexander with his companions.

Similarities between the battles fought at Thermopylae and the Persian Gates have been recognized by ancient and modern authors. The Persian Gates played the role "of a Persian Thermopylae and like Thermopylae it fell." There are also accounts that an Iranian shepherd led Alexander's forces around the Persian defenses.

The defeat of Ariobarzanes's forces at the Persian Gate removed the last military obstacle between Alexander and Persepolis. Upon his arrival at the city of Persepolis, Alexander appointed a general named Phrasaortes as successor of Ariobarzanes. Four months later, Alexander allowed the troops to loot Persepolis. A fire broke out and spread to the rest of the city. It is not clear if it had been a drunken accident, or a deliberate act of revenge for the burning of the Acropolis of Athens during the Second Greco-Persian War.