Greece itself was transformed by the Peloponnesian War. Both sides had sought out allies outside of Greece, with the Spartans ultimately allying with the Persians – formerly their hated enemies – in the final stages of the war. The Greeks as a whole were less isolated and more “cosmopolitan” by the time the war ended, meaning that at least some of their prejudices about Greek superiority were muted. Likewise, the war had inadvertently undermined the hoplite-based social and political order of the prior centuries.
Nowhere was this more true than in Sparta. Sparta had been transformed by the war, out of necessity becoming both a naval power and a diplomatic “player” and losing much of its former identity; some Spartans had gotten rich and were buying their sons out of the formerly-obligatory life in the barracks, while others were too poor to train. Likewise, the war had weakened Sparta’s cultural xenophobia and obsession with austerity, since controlling diplomatic alliances was as important as sheer military strength – this required skill, culture, and education, not just force of arms. Subsequently, the Greeks as a whole were shocked in 371 BCE when the polis of Thebes defeated the Spartans three times in open battle, symbolically marching to within sight of Sparta itself and destroying the myth of Spartan invincibility.
Across Greece, the Poleis all adopted the practice of state-financed standing armies for the first time, rather than volunteer citizen-soldiers. Likewise, the poleis came to rely on mercenaries, many of whom (ironically) went on to serve the Persians after the war wound down. Thus, between 405 BCE – 338 BCE, the old order of the hoplites and republics atrophied, replaced by oligarchic councils or tyrants in the poleis and stronger, tax-supported states. The period of the war itself was thus both the high point and the beginning of the end of “classical” Greece. Meanwhile, Persia re-captured and exerted control over the Anatolian Greek cities by 387 BCE as Greece itself was divided and weakened. Thus, even though the Persians had “lost” the Persian War, they were as strong as ever as an empire.
Despite the importance of the Peloponnesian War in transforming ancient Greece, however, it should be emphasized that not all of the poleis were involved in the war, and there were years of truce and skirmishing during which even the major antagonists were not actively campaigning. The reason that this part of Greek history is referred to as the Classical Age is that its lasting achievements had to do with culture and learning, not warfare. The Peloponnesian War ultimately resulted in checking Athens' imperial ambitions and causing the Greeks to broaden their outlook toward non-Greeks; its effects were as much cultural as political. Those effects are the topic of the next chapter.