Peloponnesian War Begins; Athenian Naval-Financial Posture

When the Peloponnesian War opened in 431 BCE, Athens believed time and sea lanes favored it. The city could avoid land battles, shelter behind the Long Walls to the Piraeus, and raid with triremes that its allies’ tribute kept in service. Thucydides quantifies this calculus: “on an average six hundred talents” flowed yearly, with “still on hand… six thousand talents of coined silver,” and more in sacred forms [6].

Thucydides also names the deeper motor—Sparta’s fear of Athenian growth as the “most true cause” of war [5]. The silver on the Acropolis translated to bronze at Zea and Mounichia; the alliances on Delos translated to patrols through the Saronic Gulf and up to the Hellespont. Across the Isthmus, Sparta watched with a land army that could not cross water without help.

The city’s geography underwrote strategy. The Piraeus made Athens a hedgehog: invulnerable to starvation so long as ships moved. Grain from Euboea and the Black Sea could reach Phaleron even if Attica’s plains burned. The color of this posture was cold metal—coin in stacks and rams on stands; the sound was the controlled chaos of embarkations as hundreds of crews boarded to the drumbeat of boatswains.

Athens had lists to match its plans. Quota stones such as IG I³ 278 recorded obligations; boards administered payments and manning [8][16]. The city could count how many oars it could pull for how long. War sharpened these capacities. When pressure mounted in the 420s, reassessments would raise totals, but the baseline confidence at the war’s start came from the steady 600 and the deep 6,000 [6][7].

Sparta sought to deny the sea strategy’s promise through allies and opportunity. But at the outset, the advantage lay with Athens’ machine: silver into ships, ships into movement. Themistocles’ original bet on the Piraeus echoed across decades to shape Pericles’ defensive strategy.

The first campaigning season tested patience on both sides. Raids, counter-raids, and naval forays measured endurance. Athens wagered that bronze, oak, and coin could outlast hoplites and harvest cycles. Thucydides’ sober account tells us how close the arithmetic seemed, and how much depended on keeping the fleet intact [5][6][8].