He invented counting, currency, weights, measures, dice and a forerunner of chess called pessoi, as well military ranks. Sometimes he is credited with discoveries in the field of wine-making and the supplementary letters of the Greek alphabet.
Agamemnon sent Palamedes to Ithaca to retrieve Odysseus, who had promised to defend the marriage of Helen and Menelaus. Paris had kidnapped Helen, but Odysseus did not want to honor his oath. He pretended to be insane and plowed his fields with salt. Palamedes guessed what was happening and put Odysseus' son, Telemachus, in front of the plow. Odysseus stopped working and revealed his sanity.
Odysseus never forgave Palamedes for sending him to the Trojan War. When Palamedes advised the Trojans to return home, Odysseus accused him of being a traitor and forged false evidence and found a fake witness to testify against him. Palamedes was stoned to death.