Meanwhile Lysander had gained the battle of Aegospotami and Sparta was supreme in the Greek world.
In 413, on the suggestion of Alcibiades, he fortified Decelea in Attica, where he remained directing operations until, after the battle of Aegospotami (405), he took the leading part in the blockade of Athens, which was ended in spring 404 by the surrender of the city.
Though reared in the height of luxury he at once determined to restore the traditional institutions of Lycurgus, with the aid of Lysander, a descendant of the victor of Aegospotami, and Mandrocleidas, a man of noted prudence and courage; even his mother, the wealthy Agesistrata, threw herself heartily into the cause.
We do not know how he rose to eminence: he first appears as admiral of the Spartan navy in 407 B.C. The story of his influence with Cyrus the Younger, his naval victory off Notium, his quarrel with his successor Callicratidas in 406, his appointment as E7rurT )€us in 405, his decisive victory at Aegospotami, and his share in the siege and capitulation of Athens belong to the history of the Peloponnesian War.
After the battle of Aegospotami (405 B.C.), Thasos again fell into the hands of the Lacedaemonians under Lysander who formed a decarchy there; but the Athenians must have recovered it, for it formed one of the subjects of dispute between them and Philip II.