When it was time for Helen of Troy to marry, many kings and princes from around the world came to seek her hand, bringing rich gifts with them, or sent emissaries to do so on their behalf.
During the contest, Castor and Pollux had a prominent role in dealing with the suitors, although the final decision was in the hands of Tyndareus.
Tyndareus was afraid to select a husband for his daughter, or send any of the suitors away, for fear of offending them and giving grounds for a quarrel.
He thus promised to solve the problem, if Tyndareus in turn would support him in his courting of 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 against whoever should quarrel with him.