And it was at a somewhat later stage of this development that they went on the expedition against Troy.
What enabled Agamemnon to raise the armament was more, in my opinion, his superiority in strength, than the oaths of Tyndareus, which bound the suitors to follow him.

Indeed, the account given by those Peloponnesians who have been the recipients of the most credible tradition is this.

First of all Pelops, arriving among a needy population from Asia with vast wealth, acquired such power that, stranger though he was, the country was called after him; and this power fortune saw fit materially to increase in the hands of his descendants.
Eurystheus had been killed in Attica by the Heraclids.

Atreus was his mother's brother; and to the hands of his relation, who had left his father on account of the death of Chrysippus, Eurystheus, when he set out on his expedition, had committed Mycenae and the government.

As time went on and Eurystheus did not return, Atreus complied with the wishes of the Mycenaeans, who were influenced by fear of the Heraclids--besides, his power seemed considerable, and he had not neglected to court the favour of the populace--and assumed the sceptre of Mycenae and the rest of the dominions of Eurystheus.