Thrasyllus continued to hold the position of strategos for several years, over a number of campaigns. Later in 410 BC, he led an Athenian fleet to attack rebellious cities on Lesbos. However, in doing so, he allowed Spartan Admiral Mindarus to slip past him into the Hellespont with the Spartan fleet in what historian Donald Kagan considers to be an error in strategic judgement. Thrasyllus pursued Mindarus with his fleet, and combined with other Athenian detachments at Sestos. From there, the Athenians (with Thrasybulus now in overall command) sailed into the Hellespont and defeated Mindarus's fleet at Cynossema, putting an end to the immediate crisis. Thrasyllus commanded a wing of the fleet in this battle and the later Athenian victory at Abydos, but then left on other detachments; after his departure Thrasybulus, Theramenes, and Alcibiades destroyed Mindarus and his fleet at Cyzicus.