Knowledge does not ensure success

From Carnage and Culture by Victor Davis Hanson, page 72. I maintain some reservations about some of Hanson's thesis but he is a good writer and always informative.

After tearing off the western portions of the empire and Egypt, Alexander in late summer 331 B.C. drove on toward Babylon in hopes of capturing the ancient city and forcing a showdown with the final military reserves of the Persian Empire. After having witnessed his own Achaemenid armies routed at Granicus (334) and again at Issus (333), as well as losing the key strongholds at Tyre and Gaza, in addition to the rich provinces of Ionia, Phoenicia, Egypt, and Cilicia, Darius understood that he must finally stay put and fight for the survival of the remaining, eastern half of his empire. He chose a small plain, more than three hundred miles north of Babylon on a small branch of the Tigris River, the Bumelus, about seventy-five miles from the town of Arbela.

Because Alexander's tactics were well known, Darius had a good idea what to expect. The king, always on the enemy right wing, would seek a gap or some flanking entry around his own left, pour through with 2,000 to 3,000 heavy horsemen, and head straight for the Persian high command, all in hopes of creating a breach through the mass, as his shield-bearing spearmen and dreaded pikemen followed. Meanwhile, Parmenio on the left would stay steadfast and pivot if need be, until the morale of the imperial army was shattered as the ruling Achaemenid clique fled for their lives. All that Darius knew, but was helpless to stop, and so the day's slaughter followed the script Darius feared and Alexander planned.

The Macedonians parted on cue for the scythed chariots — Gaugarnela seems to be the only time these much-feared but rather impractical weapons were actually used en masse in any battle — and stabbed the drivers as they sped past. Darius's elephants apparently panicked or were let through the phalanx — or never even made it to the front. Both chariots and elephants were found largely unscathed after the battle and taken as trophies. The latter after their maiden appearance at Gaugamela became a mainstay of Hellenistic warfare; the former became little more than the rhetoric of Greek romances and the sketch-pad doodles of Western engineers until the age of Leonardo da Vinci. The Persian flanking columns never quite surrounded their enemies; and the decisive charge of Indians and Persians that slammed into the Macedonian left and center now went after plunder, not Parmenio.

The consequence was that when the dust cleared on the morning of October 2, the plain of Gaugamela was an ungodly mess — Diodorus says that "the complete area of the battlefield was full of corpses" (17.50.61). Fifty thousand Persians were dead or dying—we need not believe some ancient reports of 300,000 killed—among a general detritus of wandering camp followers, crippled horses, and booty scavengers. Thousands of wounded crawled to the tiny streams and mudholes of the surrounding alluvial plains. Alexander himself returned to the battlefield to bury his dead. He collected little more than a hundred men from under the carcasses of well over a thousand Macedonian horses. Five hundred Persians had fallen at Gaugamela for every Macedonian—such were the disparities when a polyglot, multicultural force of panicked men fled on level ground before heavily armed veteran killers with pikes and seasoned cavalry, whose one worry was not to turn fainthearted in front of lifelong companions-in-arms.