(And thus well suited for Ariobarzanes's purposes.) According to historian Arrian, Ariobarzanes had a force of 40,000 infantry and 700 cavalry who faced a Macedonian force of over 10,000. However, some modern historians have claimed these figures for the Achaemenid force to be grossly exaggerated and implausible. "Encyclopædia Iranica" suggests a number of defenders of just 700 (or no more than 2,000) men based on the maximum number of troops likely at Ariobarzanes' disposal, but it notes that most modern historians follow Arrian, Curtius, and Diodorus unreservedly. 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 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. Alexander was forced to leave his dead behind to save the rest of his army—a great mark of disgrace to the Macedonians and to other Greeks who valued highly the recovery and proper burial of their fallen. 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. Ariobarzanes held the pass for a month, but Alexander succeeded in encircling the Persians in a pincer attack with Philotas and broke through the Persian defenses. Alexander and his elite contingent then attacked the force of Ariobarzanes from above in a surprise attack until the Persians could no longer block the pass. 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. 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, some historians say that this engagement cost Alexander his greatest losses during his campaign to conquer Persia.