According to the "Narratives" of the Augustan period mythographer Conon as summarised by Photius, while the two heroes were on their way to the ships, Odysseus plotted to kill Diomedes and claim the Palladium (or perhaps the credit for gaining it) for himself. He raised his sword to stab Diomedes in the back. Diomedes was alerted to the danger by glimpsing the gleam of the sword in the moonlight. He disarmed Odysseus, tied his hands, and drove him along in front, beating his back with the flat of his sword. From this action was said to have arisen the Greek proverbial expression "Diomedes' necessity", applied to those who act under compulsion. Because Odysseus was essential for the destruction of Troy, Diomedes refrained from injuring him.