(Εὐρύλοχος), a Spartan commander, in the sixth year of the Peloponnesian war, B. C. 426, was sent with 3000 heavy-armed of the allies, at the request of the Aetolians to act with them against the Messenians of Naupactus, where Demosthenes, whom they had recently defeated, was still remaining, but without any force. Eurylochus assembled his troops at Delphi, received the submission of the Ozolian Locrians, and advanced through their country into the district of Naupactus. The town itself was saved by Acarnanian succours obtained by Demosthenes, on the introduction of which, Eurylochus retired, but took up his quarters among his neighbouring allies with a covert design in concert with the Ambraciots against the Amphilochian Argives, and Acarnanians. After waiting the requisite time he set his army in motion from Proschium, and, by a wellchosen line of march contriving to elude the Amphilochians and their allies, who were stationed to oppose him, effected a junction with his friends at Olpae. Here, on the sixth day following, the enemy, under Demosthenes, attacked him. Eurylochus took the right wing opposed to Demosthenes with the Messenians and a few Athenians; and here, when already taking them on the flank, he was surprised by the assault of an ambuscade in his rear; his troops were routed, himself slain, and the whole army in consequence defeated. (Thuc. 3.100_102, 105-109.)