most valiant, after Achilles, of all the Greeks who took part in the Trojan war. He was the son of Tydeus (from whom he inherited his patronymic of Tydides) and Deipyle, and succeeded Adrastus on the throne of Argos. According to the old traditions, Tydeus perished in the famous expedition of the Seven against Thebes, leaving his son an infant. Diomedes' first act on attaining the years of manhood, was to lead another expedition against that city, which he took, and amply avenged his father's death. When war was declared against Troy, Diomede, in company with Sthenelus and Euryalus, set sail with eighty ships to avenge the injuries of Menelaus. The numerous exploits of Diomede in the Trojan war are all recorded in the glowing verse of Homer in the Iliad. He fought with the bravest heroes of the Trojan army, Hector and Enneas, both of whom he put to flight. Even the gods who did battle on the side of Troy were encountered by him with the same reckless boldness which marked his engagements with ordinary mortals. Mars himself retired wounded before him from the field of battle; and even Venus did not escape the resistless impetuosity of his attack, when she ventured to mingle in the fight in defence of her favourite Trojans. In the games instituted by Achilles to commemorate the death of Patroclus, he gained the prize in the horse-race, and defeated the mighty Ajax in single combat.

In the hands of later writers the valour and warlike exploits of Diomede received various embellishments. He was the companion of Ulysses in persuading Philoctetes to join the camp; and, along with him, carried off the palladium. In returning home he was stranded off the coast of Lycia; and on his arrival at Argos he was either too indignant at the faithlessness of his wife to remain, or was expelled by the adulterers. According to one account, he retired for a while to Ætolia, where he died; according to another, he returned to Argos; and a third tradition represents that he went to Corinth, and in attempting to return to his native city was wrecked on the coast of Italy, where he espoused the cause of the Trojans against Turnus. Hence several towns in the eastern part of Italy trace their origin to Diomed.