Menelaus Tyndareus would support him in his courting of Tyndareus’s niece Penelope, the daughter of Icarius. Tyndareus readily agreed, and Odysseus proposed that, before the decision was made, all the suitors should swear a most solemn oath to defend the chosen husband in any quarrel. Then it was decreed that straws were to be drawn for Helen’s hand. The suitor who won was Menelaus (Tyndareus, not to displease the powerful Agamemnon offered him another of his daughters, Clytaemnestra). The rest of the suitors swore their oaths, and Helen and Menelaus were married, Menelaus becoming a ruler of Sparta with Helen after
History of Sparta head. It also seems to have changed the nature of the Peloponnesian League. From that time, major decisions were discussed. Sparta was still in charge, but it now had to rally its allies in support of its decisions. After hearing a plea for help from Athens who were facing the Persians at Marathon in 490 BC, Sparta decided to honor its laws and wait until the moon was full to send an army. As a result, Sparta's army arrived at Marathon after the battle had been won by the Athenians. In the second campaign, conducted ten years later by Xerxes,