Parmenion was the son of a Macedonian nobleman Philotas. During the reign of Philip II Parmenion obtained a great victory over the Illyrians in 356 BC; he was one of the Macedonian delegates appointed to conclude peace with Athens in 346 BC, and was sent with an army to uphold Macedonian influence in Euboea in 342 BC.
Parmenion was Philip II's most trusted general, and a major influence in the formation of the tough, disciplined and professional Macedonian army whose tactics would dominate land warfare for the succeeding centuries, arguably until the battle of Pydna between Macedonia and Rome in 168 BC. The essential tactical strategy of Macedon under Philip (and perfected by Alexander) was to hold the enemy infantry and central cavalry units in place with the sarissa armed phalanx along the centre and left, while the superb cavalry forces would wheel around and attack decisively from the flank. This tactic, while by no means innovative, was performed using a variety of new military concepts of the time. One of the most effective was the phalanx technique of advancing in the oblique, which allowed a phalanx to become an offensive force. Using this formation and arming the infantry with a new weapon, the sarissa, an eighteen-foot pike, made them devastating against more conventional infantry, especially the Greek hoplites. Parmenion is generally credited today with being instrumental in the realisation of Philip's vision. Certainly his appointment as second in command to the much younger Alexander would seem to imply a great level of esteem.
In 336 BC Phillip II sent Parmenion, with Amyntas, Andromenes and Attalus and an army of 10,000 men, to make preparations for the reduction of Asia. After Alexander was recognized as king in Macedonia Parmenion himself became Alexander's second in command of the army. He is said to have acted as a foil to his commander's innovative strategies, by expertly formulating the orthodox strategy. For instance, according to Arrian's Anabasis, at the Granicus Parmenion suggested delay before the attack, as the army had already marched all day as well as for other political and geographical issues. Alexander attacked across the river regardless of this (justifiable) counsel, and gained a victory nevertheless. One historian, reconciling the accounts, has suggested that the Greeks were initially repulsed, and then stole a march on the Persians and crossed the river at night. This brought the Persian cavalry onto the field first against the Greeks the next morning, setting up a defeat in detail, as is reported in the accounts from that time. In sum, given the positions reported, either something like this occurred along with a royal cover-up, or the Persians were tactically incompetent. This theory makes more sense given the facts as known (See Battle of the Granicus) than assuming luck and poor morale and tactics on the Persian side were a significant part of this success. In any event, the outcome may have tempered any youthful brashness on the part of Alexander, for he proceeded very cautiously the next six months or so, almost dawdling as he liberated Greek cities in Asia Minor, and that muting of his aggressiveness is more in line with a near defeat.
The same source states Parmenion to have counseled a night attack in 331 BC on Darius's assembled superior forces at the Battle of Gaugamela, which Alexander took as evidence that Darius would keep his troops at the ready through the night and offer the Macedonians some advantage if they rested for a battle in daylight. Parmenion would continue to be a significant influence and commander up until the conquest of Babylon, commanding the left wing in both the battles of Issus and Gaugamela. A steady hand commanding the left was a critical part in the overall Macedonian scheme and philosophy of battle, allowing the king to strike the decisive blow.
After the conquest of Drangiana, Alexander was informed that Philotas, son of Parmenion, was involved in a conspiracy against his life. Philotas was condemned by the army and put to death. Alexander, thinking it dangerous to allow the father to live, sent orders to Media for the assassination of Parmenion. There was no proof that Parmenion was in any way implicated in the conspiracy, but he was not even afforded the opportunity of defending himself. In Alexander's defence, a disaffected Parmenion was a serious threat, especially since he was commanding an army and was stationed near Alexander's treasury and on his supply lines. Also, as head of Philotas' family Parmenion would have been held responsible for his actions, despite a lack of evidence connecting them to him. He was executed by three officers in Media in 330 BC. He was about seventy.
David Gemmell's novels Lion of Macedon and Dark Prince concern the life of Parmenion, although the fiction illustrates Parmenion as the son of a Spartan warrior and a Macedonian commoner and raised as a Spartan, though despised by his peers for his mixed blood. The story also suggests that Parmenion may have been Alexander's true father as opposed to Philip.
Steven Pressfield's novel The Virtues Of War depicts Parmenion as a loyal and brilliant servant of Macedon and a personal friend of Alexander, who only once openly protests Alexander's orientalisation.
In the 2004 film Alexander, directed by Oliver Stone, Parmenion (played by John Kavanagh) is depicted as a trusted but conservative commander and is slightly marginalised. His execution is performed (inaccurately) by Cleitus the Black.
The Hasbro board game Heroscape includes a Parmenio figure.