Demosthenes, an Athenian general, prominent in the Peloponnesian war. He was sent in 426 B. C, with Procles, in command of 30 ships, on the annual cruise around the Peloponnesus. Through the representations of the Messenians he was induced to attempt the reduction of the AEtolians, but his Locrian allies failing him, he met with a disastrous defeat. In the same year he was successful against the Ambraciotes and their Spartan allies at Olpse, and again at the battle of Idomene, where much spoil was taken. In 425 he captured a Spartan force which had besieged him in a fort he had built at Pylos in Messenia; but the glory of this success was claimed by Cleon, who had been sent to supersede him. In 424 he possessed himself by a stratagem of the walls connecting Megara and Nisaea, and shortly after took the latter place. In the same year he failed in an attempt on Boeotia, and was repulsed in a descent on the territory of Sicy-on. In 413 he was sent with Eurymedon in command of reinforcements for the Athenians under Nicias who were besieging Syracuse. On the disastrous defeat of the Athenians in a night attack, he counselled immediate withdrawal; but other advice prevailed; a fatal delay took place; Gylippus returned with re-enforcements for the besieged, and the Athenians were obliged to retreat by land.

While defending the rear against the enemy he was surrounded and captured. His death was decreed by the Syracusan assembly, and he and Nicias suffered at the same time.