TPeloponnesian War between Sparta and Athen War between Sparta and Athen and how important it was for both of them to win. How winning/losing would affect both cities.
Each stood at the head of alliances that, between them, included nearly every Greek city-state. The fighting engulfed virtually the entire Greek world, and it was properly regarded by Thucydides, whose contemporary account of it is considered to be among the world’s finest works of history, as the most momentous war up to that time. The Athenian alliance was, in fact, an empire that included most of the island and coastal states around the northern and eastern shores of the Aegean Sea.