After the voluntary abdication of Oedipus, his two sons, Eteocles and Polynices, took possession of the crown and reigned over the city of Thebes. But Eteocles, being an ambitious prince, soon seized the reins of government himself, and expelled his brother from the throne.
Polynices now repaired to Argos, where he arrived in the dead of night. Outside the gates of the royal palace he encountered Tydeus, the son of Oeneus, king of Calydon. Having accidentally killed a relative in the chase, Tydeus was also a fugitive; but being mistaken by Polynices in the darkness for an enemy, a quarrel ensued, which might have ended fatally, had not king Adrastus, aroused by the clamour, appeared on the scene and parted the combatants.
By the light of the torches borne by his attendants Adrastus observed, to his surprise, that on the shield of Polynices a lion was depicted, and on that of Tydeus a boar. The former bore this insignia in honour of the renowned hero Heracles, the latter in memory of the famous Calydonian boar-hunt. This circumstance reminded the king of an extraordinary oracular prediction concerning his two beautiful daughters, Argia and Deipyle, which was to the effect that he would give them in marriage to a lion and a boar. Hailing with delight what he regarded as an auspicious solution of the mysterious prophecy, he invited the strangers into his palace; and when he heard their history, and had convinced himself that they were of noble birth, he bestowed upon Polynices his beautiful daughter Argia, and upon Tydeus the fair Deipyle, promising at the same time that he would assist both his sons-in-law to regain their rightful patrimony.
The first care of Adrastus was to aid Polynices in regaining possession of his lawful share in the government of Thebes. He accordingly invited the most powerful chiefs in his kingdom to join in the expedition, all of whom readily obeyed the call with the exception of the king's brother-in-law, Amphiaraus, the seer. As he foresaw a disastrous termination to the enterprise, and knew that not one of the heroes, save Adrastus himself, would return alive, he earnestly dissuaded the king from carrying out his project, and declined to take any part in the undertaking. But Adrastus, seconded by Polynices and Tydeus, was obstinately bent on the achievement of his purpose, and Amphiaraus, in order to escape from their importunities, concealed himself in a hiding-place known only to his wife Eriphyle.
Now on the occasion of the marriage of Amphiaraus it had been agreed, that if he ever differed in opinion with the king, his wife should decide the question. As the presence of Amphiaraus was indispensable to the success of the undertaking, and, moreover, as Adrastus would not enter upon it without "the eye of the army," as he called his brother-in-law, Polynices, bent on securing his services, determined to bribe Eriphyle to use her influence with her husband and to decide the question in accordance with his wishes. He bethought himself of the beautiful necklace of Harmonia, wife of Cadmus, which he had brought with him in his flight from Thebes. Without loss of time he presented himself before the wife of Amphiaraus, and held up to her admiring gaze the glittering bauble, promising that if she revealed the hiding-place of her husband and induced him to join the expedition, the necklace should be hers. Eriphyle, unable to withstand the tempting bait, accepted the bribe, and thus Amphiaraus was compelled to join the army. But before leaving his home he extorted a solemn promise from his son Alcmæon that, should he perish on the field of battle, he would avenge his death on his mother, the perfidious Eriphyle.
Seven leaders were now chosen, each at the head of a separate detachment of troops. These were Adrastus the king, his two brothers Hippomedon and Parthenopæus, Capaneus his nephew, Polynices and Tydeus, and Amphiaraus.
When the army was collected they set out for Nemea, which was at this time governed by king Lycurgus. Here the Argives, being short of water, halted on the outskirts of a forest in order to search for a spring, when they saw a majestic and beautiful woman seated on the trunk of a tree, nursing an infant. They concluded from her noble and queenly appearance that she must be a goddess, but were informed by her that she was Hypsipile, queen of the Lemnians, who had been carried away captive by pirates, and sold as a slave to king Lycurgus, and that she was now acting as nurse to his infant son. When the warriors told her that they were in search of water, she laid the child down in the grass, and led them to a secret spring in the forest, with which she alone was acquainted. But on their return they found, to their grief, that the unfortunate babe had been killed during their absence, by a serpent. They slew the reptile, and then collecting the remains of the infant, they buried them with funereal honours and proceeded on their way.
The warlike host now appeared before the walls of Thebes, and each leader placed himself before one of the seven gates of the city in readiness for the attack. Eteocles, in conjunction with Creon, had made due preparations to repel the invaders, and had stationed troops, under the command of trusty leaders, to guard each of the gates. Then, according to the practice of the ancients of consulting soothsayers before entering upon any undertaking, the blind old seer Tiresias was sent for, who, after carefully taking the auguries from the flight of birds, declared that all efforts to defend the city would prove unavailing, unless the youngest descendant of the house of Cadmus would offer himself as a voluntary sacrifice for the good of the state.
When Creon heard the words of the seer his first thought was of his favourite son Menœceus, the youngest scion of the royal house, who was present at the interview. He therefore earnestly implored him to leave the city, and to repair for safety to Delphi. But the gallant youth heroically resolved to sacrifice his life for the benefit of his country, and after taking leave of his old father, mounted the city walls, and plunging a dagger into his heart, perished in the sight of the contending hosts.
Adrastus now gave his troops the word of command to storm the city, and they rushed forward to the attack with great valour. The battle raged long and furiously, and after heavy losses on both sides the Argives were routed and put to flight.
After the lapse of some days they reorganized their forces, and again appeared before the gates of Thebes, when Eteocles, grieved to think that there should be such a terrible loss of life on his account, sent a herald into the opposite camp, with a proposition that the fate of the campaign should be decided by single combat between himself and his brother Polynices. The challenge was readily accepted, and in the duel which took place outside the city walls, in the sight of the rival forces, Eteocles and Polynices were both fatally wounded and expired on the field of battle.
Both sides now claimed the day, and the result was that hostilities recommenced, and soon the battle raged with greater fury than ever. But victory at last declared itself for the Thebans. In their flight the Argives lost all their leaders, Adrastus excepted, who owed his safety to the fleetness of his horse Arion.
By the death of the brothers, Creon became once more king of Thebes, and in order to show his abhorrence of the conduct of Polynices in fighting against his country, he strictly forbade any one to bury either his remains or those of his allies. But the faithful Antigone, who had returned to Thebes on the death of her father, could not endure that the body of her brother should remain unburied. She therefore bravely disregarded the orders of the king, and endeavoured to give sepulture to the remains of Polynices.
When Creon discovered that his commands had been set at defiance, he inhumanly condemned the devoted maiden to be entombed alive in a subterranean vault. But retribution was at hand. His son, Hæmon, who was betrothed to Antigone, having contrived to effect an entrance into the vault, was horrified to find that Antigone had hanged herself by her veil. Feeling that life without her would be intolerable, he threw himself in despair on his own sword, and after solemnly invoking the malediction of the gods on the head of his father, expired beside the dead body of his betrothed.
Hardly had the news of the tragic fate of his son reached the king, before another messenger appeared, bearing the tidings that his wife Eurydice, on hearing of the death of Hæmon, had put an end to her existence, and thus the king found himself in his old age both widowed and childless.
Nor did he succeed in the execution of his vindictive designs; for Adrastus, who, after his flight from Thebes, had taken refuge at Athens, induced Theseus to lead an army against the Thebans, to compel them to restore the dead bodies of the Argive warriors to their friends, in order that they might perform due funereal rites in honour of the slain. This undertaking was successfully accomplished, and the remains of the fallen heroes were interred with due honours.