The modern image of war, peace and international relations in ancient Greece is very much the image that the historian Thucydides sought to project in his history of the Peloponnesian War (431-404 BC): a world in which every state was always out to increase its power at the expense of others and where unscrupulous power politics had reduced all ethical concerns to mere pretence; a world in which war was the norm and annihilation the price of defeat. Ancient Greece thus seems to ﬁt perfectly the extreme ‘realist’ scenario of an anarchic system of states constantly struggling for survival and power. Yet Thucydides’ own account of the war shows that the hard-nosed analyses which he offered were one-sided, and other evidence conﬁrms that Greek international relations were much more complex, and rather less brutal, than he suggested. There was indeed constant tension and frequent warfare between the city-states throughout the archaic and classical periods (c.700-500 and 500-300 BC), but we cannot follow Thucydides or modern realists in attributing this to simple ‘laws of human nature’. Relations between political communities in Ancient Greece were shaped by a culture which did much both to encourage and inhibit the eruption of armed conﬂict.