One of the most celebrated of the adventures of Theseus is his expedition against the Amazons. He assailed them before they had recovered from the attack of Hercules, and carried off their queen Antiope. The Amazons in their turn invaded the country of Athens and penetrated into the city itself; and the final battle in which Theseus overcame them was fought in the very midst of the city. This battle was one of the favourite subjects of the ancient sculptors, and is commemorated in several works of art that are still extant.
The friendship between Theseus and Pirithous was of a most intimate nature, yet it originated in the midst of arms. Pirithous had made an irruption into the plain of Marathon, and carried off the herds of the king of Athens. Theseus went to repel the plunderers. The moment Pirithous beheld him, he was seized with admiration; he stretched out his hand as a token of peace, and cried, "Be judge thyself- what satisfaction dost thou require?" "Thy friendship," replied the Athenian, and they swore inviolable fidelity. Their deeds corresponded to their professions, and they ever continued true brothers in arms. Each of them aspired to espouse a daughter of Jupiter. Theseus fixed his choice on Helen, then but a child, afterwards so celebrated as the cause of the Trojan war, and with the aid of his friend he carried her off. Pirithous aspired to the wife of the monarch of Erebus; and Theseus, though aware of the danger, accompanied the ambitious lover in his descent to the underworld. But Pluto seized and set them on an enchanted rock at his palace gate, where they remained till Hercules arrived and liberated Theseus, leaving Pirithous to his fate.
After the death of Antiope, Theseus married Phaedra, daughter of Minos, king of Crete. Phaedra saw in Hippolytus, the son of Theseus, a youth endowed with all the graces and virtues of his father, and of an age corresponding to her own. She loved him, but he repulsed her advances, and her love was changed to hate. She used her influence over her infatuated husband to cause him to be jealous of his son, and he imprecated the vengeance of Neptune upon him. As Hippolytus was one day driving his chariot along the shore, a sea-monster raised himself above the waters, and frightened the horses so that they ran away and dashed the chariot to pieces. Hippolytus was killed, but by Diana's assistance AEsculapius restored him to life. Diana removed Hippolytus from the power of his deluded father and false stepmother, and placed him in Italy under the protection of the nymph Egeria.
Theseus at length lost the favour of his people, and retired to the court of Lycomedes, king of Scyros, who at first received him kindly, but afterwards treacherously slew him. In a later age the Athenian general Cimon discovered the place where his remains were laid, and caused them to be removed to Athens, where they were deposited in a temple called the Theseum, erected in honour of the hero.
The queen of the Amazons whom Theseus espoused is by some called Hippolyta. That is the name she bears in Shakespeare's "Midsummer Night's Dream,"- the subject of which is the festivities attending the nuptials of Theseus and Hippolyta.