The Peloponnesian War, fought between 431 and 404 BCE, was a devastating conflict primarily between the city-states of Athens and Sparta, along with their respective allies. Estimates of the total number of deaths vary widely due to the lack of comprehensive records from that era. However, historical accounts suggest that military casualties were significant, with tens of thousands of soldiers perishing in battles and campaigns. Additionally, the war caused widespread suffering and loss of life among civilians, exacerbated by famine and disease, particularly the plague that struck Athens in 430 BCE.
Some historians suggest that the total number of deaths, including both military personnel and civilians, could reach as high as 100,000 or more. Ultimately, the Peloponnesian War had lasting effects on the Greek world, leading to a shift in power and the decline of Athenian dominance.