The Battle of Solinus was a naval battle of the Peloponnesian War which was fought off Mykonos in 424 BC.
The failure of the Athenian invasion of Naxos at the Battle of Colinus forced the Athenian forces in the Aegean Sea to assume a defensive posture. Taking advantage of this, the Spartan mercenary Kassandra decided to strike at the source of the Athenian naval assaults: the Silver Islands. She infiltrated the Miltiades Fort on Mykonos and assassinated the pro-Athenian leader Alphios the Living Riddle, weakening the islands' defenses. The Spartans sent a fleet from Naxos to attack Mykonos, and Kassandra lent the support of her ship, the Adrestia, to the Spartan invasion fleet. In the ensuing battle, the Spartans sunk all four Athenian garrison ships, paving the way for the Spartans to install a garrison on the Silver Islands.