Why did the Spartans start the Peloponnesian War?

Answer 1

Fear - They feared that the rise of Athenian power would consume them - weighing the balance of power as it existed at the time, and what they saw as Athens continued rise in power - the window of opportunity to win a war against them was closing - in the end, they went to war because they feared the growing power of their neighbor to the north and their growing influence in the region.

Answer 2

they didn't like each other
An overconfident Athens, having turned Delian League for the war against the Persian Empire into an empire of its own, became aggressive to other cities, and eventually tried to ruin its neighbour Megara. That city was a member of the Peloponnesian League led by Sparta, and Megara appealed for help. Sparta appealed to Athens to back off, Athens persisted and war broke out.

Answer 3

Athens started the Peloponnesian War by its interference in the affairs of other cities - at Corcyra, Potidaia and Megara. It set out to bankrupt Megara, a member of the Spartan-led Peloponnesian League. Sparta asked Athens to back off, Athens persisted, war ensued.

Answer 4

a war called the peloponnesian war