Tyndareus
Τυνδάρεος
The Spartan king who made all of Helen's suitors swear an oath — the future draft notice for a war.
King of Sparta and husband of Leda. Because Zeus intruded as a swan, the fatherhood of the four children — Helen, Clytemnestra, Castor, Polydeuces — is split half and half with Zeus.
When Helen's suitors grew so numerous that every king in Greece seemed to be among them, he borrowed Odysseus's cunning and made them all swear: whoever was chosen, the rest would defend the marriage.
When Helen left for Troy, this "Oath of Tyndareus" became the summons that dragged all of Greece into war.
SourcesApollodorus, Library