In tile same year. 411 BC, Thrasyllus commanded the left wing of the fleet at the battle of Cynossema, in which the Athenians defeated the Peloponnesians; and somewhat later, after the victory gained by the Athenians over the Lacedaemonian fleet near Abydus, he was despatched to Athens to bear the good news and to ask for supplies. Some time after his arrival, Agis having, in a foray from Deceleia, advanced too near the walls of the city, Thrasyllus led out the Athenians against him and obtained a slight advantage, in consequence of which his countrymen the more readily voted him a reinforcement both of men and ships. With these he sailed early in 409 BC to Samos, whence he proceeded to the coast of Asia and attacked the town of Pygela without success. Within a few days, however, Colophon surrendered to him, and he then advanced into Lydia, and having ravaged the country, proceeded by sea against Ephesus, but here he was defeated and driven back to his ships by the forces of the Ephesians, united with those of Tissaphernes and the Syracusans; and after sailing to Notium where he buried his dead, he steered his course for Lesbos. Here, while anchoring at Methymna, he observed the Syracusan squadron sailing by, whereupon he attacked it, captured four ships with their crews, and chased the rest back to Ephesus. He then continued his voyage to Sestus, where He joined the force under Alcibiades, and the whole fleet crossed over together to Lampsacus; but the troops of Alcibiades, who had not sustained any defeat. refused to serve in the same ranks with those of Thrasyllus, conquered as they bad been at Ephesus; nor was this feeling removed till their common success in the ensuing winter against Pharnabazus near Abydus.

In 408 BC Thrasyllus was engaged with Alcibiades in the successful operations at Chalcedon, which induced Pharnabazus to accept terms of accommodation from the Athenians He probably shared also in the siege and reduction of Byzantium in the same year. and in 407 BC he led home to Athens a portion of the triumphant armament. Not long after, he was.; one of the generals who were appointed to supersede Alcibiades after the battle of Notium, and was present in that capacity at Arginusae in 406 BC. After the battle it was he who proposed to leave 47 galleys behind to save the mien from the wrecks, while the main body of the fleet should sail against the ships of the enemy, which were blockading Mytileine. He was also among the six generals who returned to Athens and were shamfully put to death by the people through the intrigues of Theramenes. It should be observed that Diodorus, in his account of several of the above events, substitutes by an error, the name of Thrasybulus for that of Thrasyllus.

(Thuc. viii. 73, 75, 76, 104, 105; Xen. Hell. i. 1. §§ 8, 33, 34, 2. §§ 1-17, . 3. §§ 4, &c., 14, &c., 4. § 10, 5. § 16, 6. § 30, 7. §§ 2.29, 34; Plat. Theag. p. 129 ; Plut. Alc. 29-31 ; Diod. xiii. 64, 66, 74, 101, 102; Palm. and Wess. ad Diod. xiii. 74.)