6. The Battle of Mantinea was the largest land battle of the Peloponnesian War
Argos, a powerful state, managed to form a coalition of democratic states within the Peloponnese. Supported by a small Athenian force, they moved to capture the city of Tegea, near Sparta. This led to the Battle of Mantinea in 418 BCwhich was the largest land battle of the Peloponnesian War. Sparta and its allies completely defeated forces led by Argos and Athens thus breaking the democratic alliance and re-establishing its dominance in the Peloponnese.
7. Sicilian Expedition was a disaster for Athens and turned the tide in Sparta’s favor
In 415 BC, Athens sent a massive expeditionary force to Sicily when one of its allies was attacked by Syracuse, the most powerful state in the region. The Peloponnesian League kept sending reinforcements to Sicily. The mighty Athenian expedition was thoroughly defeated and their entire force was killed or enslaved. Such was the magnitude of Athenian loss in the Sicilian Expedition that it was widely believed that Athenian Empire was defeated for good.