Achilles was a combatant of the Trojan War. He was the son of Thetis the Goddess and the mortal Peleus, King of Pthia. His maternal grandparents were Nereus and his wife Doris. Nereus was a son of Pontus and Gaea. Doris was a daughter of Oceanus and Tethys.
When Achilles was born, his loving mother Thetis wished to make him immortal, and for that purpose she dipped him in the waters of the river Styx. But others affirm that she, without the knowledge of the child's father, used to put the babe in the fire by night in order to destroy the mortal element which Achilles had inherited from Peleus , while anointing him with ambrosia during the day. But when Peleus saw the child writhing on the fire, he cried out, thus preventing Thetis from accomplishing her purpose (Apd.3 .13.6). Then she threw the screaming child to the ground, and leaving both husband and son, departed to the Nereids and never returned again to Phthia, though she always kept an eye on her offspring.
When Achilles was a child, his father brought him to Chiron , the wise Centaur living in Mount Pelion, who educated him and fed him on the inwards of lions and wild swine, the marrows of bears, milk and honey. And when Achilles was nine years old, the seer Calchas , whom Agamemnon has called 'prophet of evil', declared that Troy could not be taken without him. This is one of the reasons why Achilles came to Troy ; for he, who had not been among the Suitors of Helen , was not bound by the Oath of Tyndareus .
From then on there was no rest for Thetis, the loving mother. For she knew that the Judgement of Paris would cause the abduction of Helen , which would cause the Trojan War , which would lead to Achilles' death. And yet she looks into the interstices of fate hoping for a way out, and asks Poseidon to send a storm and let the Trojan fleet sink on its way to Sparta . But not even the gods can change what fate has ordained.
For the pious Centaur Chiron, who was not a drunkard like other Centaurs, and who never had used his weapons against a man, and who spent his old age learning about herbs and teaching to play the lyre to his pupils, Achilles proved to be a difficult task. For when the boy had for ever left his tender years behind him, he started wandering wherever he pleased, disobeying his teacher, and indulging in what he thought to be a good time, plundering the homes of neighbouring Centaurs, stealing their cattle, and provoking a growing anger in the whole province. That is why, when Thetis, being afraid of what was being planned by fate and by Zeus (who had issued his decree of war), came to Chiron to see her sweet darling son Achilles, the Centaur begged her to take him away.
So Thetis, seeing that it was fated that Achilles should perish in the war, and still looking for a way out, disguised him as a female and entrusted him to king Lycomedesof Scyros ( the island in the Aegean Sea northeast of Euboea), the same man who is believed to have treacherously murdered his guest, the exiled King Theseus of Athens. Achilles, they say, would not accept to be dressed like a girl, no matter how much her mother worked on his rough heart, until he noticed that this was the only way to come closer to the king's daughter Deidamia. Having accepted the looks of a girl, he was presented by Thetis to the king as Achilles' sister. And the king swallowed the lie, for a mortal cannot avoid being deceived by a deity. But some have thought that the story of Achilles disguised under the name Pyrrha in Scyros is absurd, and argue that Achilles lived in that island because he had conquered it.
When war approached, the trick of Achilles being his own sister was discovered by Odysseus , who, for the purpose of revealing Achilles' true identity, used a trumpet. He reasoned that a girl would not react to its sound as a man does. In that way Achilles, then fifteen years old, became Leader of the Myrmidons, a people of Phthia, to lead them against Troy, along with the other allies. Nevertheless Destiny (so they say) left, at any moment, two courses for Achilles: to stay in the siege of Troy, die and win everlasting fame, or go home and fameless have a long life. That is how Achilles sailed from Scyros and went to the war, leaving in grief the pregnant Deidamiawhom he married before his departure.
Achilles arrived with his fifty or sixty ships to the harbour of Aulis, opposite to the island of Euboea, where the powerful Achaean fleet was gathering in order to sail against Troy and obtain through persuasion or by force the restoration of Helen and the Spartan property, both stolen by the seducer Paris. But because of the inconvenience posed by the winds, the fleet at Aulis could not leave. It was then that the seer Calchas concluded that human sacrifice could make the weather better, and consequently recommended Agamemnon to let his daughter Iphigenia die in the altar. Following the prophet's advice, the king wrote a treacherous letter asking his daughter to leave Mycenae and come to Aulis so that she should marry Achilles, who himself knew nothing about the king's scheming. When Iphigenia or the deer which Artemis substituted, was sacrificed at Aulis, the fleet left and came to Tenedos, an island off the coast of the Troad.
There Achilles killed King Tenes, though Thetis had warned him not to do so, as it was known that the man who killed Tenes would die by Apollo's hand. As it is said, Thetis even commissioned a servant to always remind Achilles not to kill this man who was honoured by Apollo or perhaps was his son. But Achilles, for whom getting and keeping sweethearts was a matter of the utmost importance, came across Tenes' sister Hemithea. When her brother defended her, she escaped, and then Achilles in anger killed Tenes. And having thus done what he should not, he also killed the servant, because he, although present, had not reminded him of his mother's warning. Thetis also warned Achilles not to be the first to land on Trojan land, for it had been prophesied that the first to land would be the first to die. This Achilles was able to avoid. The first among the Achaeans to land was unlucky Protesilaus, who, having killed several defenders, was also the first to die.
Now, it has been conjectured by military expertise, that the Achaeans, on their arrival to enemy land obtained a victory; for otherwise they could not have landed or even less built fortifications. But at the same time, not having enough supplies, they dispersed being obliged to resort to plunder, piracy and perhaps even agriculture. It was lack of supplies, then, that led to the dispersion of the army, making it possible for the Trojans to defend their city for ten years, although many other cities in Asia Minor were destroyed by the invaders. During this phase Achilles sacked the islands of Tenedos and Lesbos, and the cities of Thebe, Antandrus, Adramytium, and Lyrnessus; and reaching far to the south, he sacked also Cyme, Phocaea, Smyrna, Clazomenae and Colophon.
In the tenth year of the war, King Agamemnon delivered himself to arrogance, humiliating a priest of Apollo who had come to ransom his daughter, Agamemnon's prize. So Apollo, although called 'the bright one', came down from Olympus darker than night, and let a pestilence decimate the Achaean army, thus avenging the humiliated priest. When the seer Calchas declared that Agamemnon's way of treating Apollo's priest was to blame, the king, though insulting the seer too, agreed to renounce his girl, but at the same time annouced his intention of compensating himself by taking someone else's prize. On hearing the king's threat, Achilles called him a shameful schemer and a man always ready to take the lion's share and to profit by others' efforts piling wealth for himself. Agamemnon was then utterly displeased, and answered by letting Achilles know that, by taking away his sweetheart Briseis, he would teach him a lesson in both power and kingship. Having heard the new threat, Achilles considered killing Agamemnon, but while he pondered, Athena came from heaven, and, invisible to the others present, seized him by his hair and stayed his anger. Keeping his word, Agamemnon let Achilles' sweetheart Briseis be fetched and taken away from his tent. This is what allowed wrath to make its nest in Achilles' heart, keeping him in a dark mood and away from the battlefield. Accordingly, the host of Myrmidons that had followed him to Troy became an idle mass.
But in the view of Thetis nothing could be more unfair. For Achilles' life was fated to be short, and she could not see any justice in letting it be miserable too. So in order to redress what she deemed to be an unjust state of affairs, she went to see Zeus , and putting her left arm round his knees while her right hand touched his chin, asked of him compensation for her son. Zeus both listened to this prayer and granted it, and that is why the Achaeans suffered many defeats in the battlefield; for the god resolved that they should learn to honour the man they had outraged.
As time went by and the Trojans became more and more dangerous, Agamemnon agreed to appease Achilles' wrath. It is for this purpose that he offered him the seven tripods, the seven women, the seven cities, and many other gifts including Briseis, whom Agamemnon claimed he had not touched (and no one has ever contradicted his assertion). But gifts, profit and riches were the same as nothing to Achilles, for whom friendship, honour, and being of one heart, was far more important. And so, convinced that the king would for ever lack the means to appease his offended heart, he turned down the gifts of the man who had committed against him the kind of crime they had come to Troy to avenge. And because no agreement was reached between the king, who thought that wealth is coveted by all, and the warrior, who was proud of his own heart, new defeats fell upon the Achaeans.
But when the Trojans, having come closer, succeeded in setting fire to the ships, Achilles consented to send his close friend Patroclus to battle again in order to stop their offensive. And when Patroclus, according to heaven's decree, was killed by Hector in battle, Achilles came back to life again, although life had no more meaning for him. Achilles asked his mother to let him go and seek death, since he had not been able to save Patroclus from dying. She then, knowing that heaven had decided that Achilles would die shortly after Hector' s death, began to accept her son's fate. It is then that Achilles regretted bitterly to have sat idle by his ships, wasting his force and eluding his duty. For, as it has been said, Achilles forgot that he had come to Troy not to have a good time with girls, but in order to fight. Consequently, he now felt that, by letting himself be deluded by the poisoned honey of anger, he had acted like a man with no wit, and that, though always resenting that mistake, he could still put things aright, by coming back to battle and seeking Hector the destroyer of his dearest friend Patroclus. Thetis promised to fetch a new armour from Hephaestus for him, since the first one had been taken by Hector when he killed Patroclus who wore it.
While Thetis fetched the new armour for his son, Achilles called a council and in it, without asking anything in return, he ended his feud with Agamemnon,, who acknowledging that he himself had been the one whom the gods had blinded, declared that he was ready to make amends and pay Achilles the compensation of the seven tripods, the seven women, the seven cities, and all other magnificent gifts which included Achilles' sweetheart Briseis. But Achilles declined all the offers. When the new armour arrived, Achilles sought Hector and, having killed him, outraged his body, intending to give it to the dogs, until, by the will of the gods, he was convinced to accept a ransom from King Priam of Troy, who humiliated himself in front of the man who had killed his son. And as it had been predicted, shortly after the death of Hector, Achilles himself was killed. But before that, Achilles slew many others.
Later, Achilles confronted the amazon queen Penthesilea and the ethiopian king Memnon, who was also a demigod.
Some say that Achilles was slain by Paris and Apollo at the Scaean gate at Troy. But others say that it was Apollo alone who took his life. Still others say that Achilles fell in love with Polyxena, daughter of Priam, and when Achilles, who had sought her in marriage, came for an interview, he was treacherously killed by Paris' men or by Paris and Deiphobus.