What caused the Peloponnesian War?

Athens was the greatest sea power, and Sparta the greatest land power in 5th century BC Greece.

In the first phase, the Archidamian War, Sparta launched repeated invasions of Attica, while Athens took advantage of its naval supremacy to raid the coast of the Peloponnese attempting to suppress signs of unrest in its empire.

This period of the war ended in 421 BC, with the signing of the Peace of Nicias. That treaty, however, was soon undermined by renewed fighting in the Peloponnese. In 415 BC, Athens dispatched a large force to attack Syracuse in Sicily. The attack failed, with the destruction of the entire force, in 413 BC.

This ushered in the final phase of the war, generally referred to either as the Decelean War, or the Ionian War. In this phase, Sparta, now receiving support from Persia, supported rebellions in Athens' subject states in the Aegean Sea and Ionia, undermining Athens' empire, and, eventually, depriving the city of naval supremacy. The destruction of Athens' fleet at Aegospotami effectively ended the war, and Athens surrendered in the following year.

The Peloponnesian War reshaped the Ancient Greek world. Athens, the strongest city-state in Greece before the war started, was reduced to a state of near-complete subjection. Sparta became the leading power of Greece.

People arguing about how to spell Peloponnesian. It got out of hand.

Athens as bullying Corinth,a member of the Peloponnesian League (led and dominated by Athens).

Sparta had to back Corinth against Athens,or would lose credibility with other members of the Peloponnesian League who might then decide to switch support to Athens.

Independent city-states were competing for resources and cultural influence.
Athens abuse of the Delian League for its own prosperity caused a great deal of resentment.
Sparta challenged Athen's influence.

Was it in the time of the Roman Empire? Maybe twrritoeieL disputes