The feud between Miletus and Samos broke out into open strife during the Lelantine War (7th century BC), with which we may connect a Samian innovation in Greek naval warfare, the use of the trireme. The result of this conflict was to confirm the supremacy of the Milesians in eastern waters for the time being; but in the 6th century, the insular position of Samos preserved it from those aggressions at the hands of Asiatic kings to which Miletus was henceforth exposed. About 535 BC, when the existing oligarchy was overturned by the tyrant Polycrates, Samos reached the height of its prosperity. Its navy not only protected it from invasion but also ruled supreme in Aegean waters. The city was beautified with public works, and its school of sculptors, metal-workers and engineers achieved high repute.