Lysander was one of the Heraclidae at Sparta, but not a member of the royal families. Not much is known about his early life. His family was not wealthy, and we don't know how Lysander came to be entrusted with military commands.
The Spartan Fleet in the Aegean
When Alcibiades rejoined the Athenian side towards the end of the Peloponnesian War, Lysander was put in charge of the Spartan fleet in the Aegean, based at Ephesus (407). It was Lysander's decree that merchant shipping put into Ephesus and his foundation of shipyards there, that started its rise to prosperity.
Persuading Cyrus to Help the Spartans
Lysander persuaded Cyrus, the Great King's son, to help the Spartans. When Lysander was leaving, Cyrus wanted to give him a present, and Lysander asked for Cyrus to fund an increase in the sailors' pay, thus inducing sailors serving in the Athenian fleet to come over to the higher-paying Spartan fleet.
While Alcibiades was away, his lieutenant Antiochus provoked Lysander into a sea battle which Lysander won. The Athenians thereupon removed Alcibiades from his command.
Callicratides as Lysander's Successor
Lysander gained partisans for Sparta amongst the cities subject to Athens by promising to install decemvirates, and promoting the interests of potentially useful allies amongst their citizens. When the Spartans chose Callicratides as Lysander's successor, Lysander undermined his position by sending the funds for the increase in payback to Cyrus and taking the fleet back to the Peloponnese with him.
The Battle of Arginusae (406)
When Callicratides died after the battle of Arginusae (406), Sparta's allies requested that Lysander is made admiral again. This was against Spartan law, so Aracus was made admiral, with Lysander as his deputy in name, but the actual commander.
Ending the Peloponnesian War
It was Lysander who was responsible for the final defeat of the Athenian navy at Aegospotami, thus ending the Peloponnesian War. He joined the Spartan kings, Agis and Pausanias, in Attica. When Athens finally succumbed after the siege, Lysander installed a government of thirty, later remembered as the Thirty Tyrants (404).
Unpopular Throughout Greece
Lysander's promotion of his friends' interests and vindictiveness against those who displeased him made him unpopular throughout Greece. When the Persian satrap Pharnabazus complained, the Spartan ephors recalled Lysander. There resulted in a power struggle within Sparta itself, with the kings favoring more democratic regimes in Greece in order to diminish Lysander's influence.
King Agesilaus Instead of Leontychides
On the death of King Agis, Lysander was instrumental in Agis' brother Agesilaus being made king instead of Leontychides, who was popularly supposed to be Alcibiades' son rather than the king's. Lysander persuaded Agesilaus to mount an expedition to Asia to attack Persia, but when they arrived in the Greek Asian cities, Agesilaus grew jealous of the attention paid to Lysander and did everything he could to undermine Lysander's position. Finding himself unwanted there, Lysander returned to Sparta (396), where he may or may not have started a conspiracy to make the kingship elective amongst all Heraclidae or possibly all Spartiates, rather than confined to the royal families.
War Between Sparta and Thebes
War broke out between Sparta and Thebes in 395, and Lysander was killed when his troops were surprised by a Theban ambush.