In Episode 5 of Naval History Podcast, we begin our multi-part examination of the Peloponnesian War, fought from 431 to 404 BC. This part covers the nature and causes of the war, beginning in the final years of the Greco-Persian War, as well as the opening phase of the Peloponnesian War itself (the Archidamian War of 431-421 BC), concluding with the Peace of Nicias in 421 BC.