Book VII begins with another battle for Syracuse, in which Athens is defeated. Nicias sends emissaries home to Athens to warn that the enemies are seeking to exploit the weakness of their deteriorating naval power. He asks whether or not they should consider sending reinforcements, and if they will accept his resignation.
Athens sends Nicias reinforcements, and they reject his request to resign. Meanwhile Sparta opens a second front by invading Athens, and Athens begins to face mounting casualties. Thucydides notes the “foremost decline” of Athens as follows:
“Indeed the first and foremost cause of the ruin of the Athenian army was the capture of Plemmyrium [by the Syracusans]…beside the general impression o0. f dismay and discouragement placed upon the army” (7.24).
The stress of the dual war increased strain on Athens. They fail to make ground in Syracuse while Demosthenes leads a failed moonlight ambush that left Athenian soldiers scattered and confused, confusing the enemy with their Dorian allies. Demosthenes argues they should return home, while Nicias refuses to admit of any weakness. Ultimately, the Athenians are demoralized and embarrassed by the loss at Syracuse, culminating in Nicias’s surrender. Nicias, who Thucydides praises for his virtue, along with Demosthenes are butchered by the Syracusans, despite the will of the general who preferred to bring them to Sparta instead. The defeat is called a “total” destruction as seven thousand are captured, imprisoned, and enslaved. Thus ends Book VII.
Upon receiving word of Athens’s destruction in Sicily, they are shocked but decide to build up their naval power. Alcibiades encourages several revolts from Athens. Meanwhile, Sparta signs a treaty with Persia. Then Alcibiades betrays Sparta. An oligarchy takes over Athens.
Book VIII abruptly ends in 411 BC, an unfinished work by Thucydides. It ends before Thucydides can tell the story of Athens ultimately being crushed by Lysander’s superior tactical skills at Aegospotami. The ensuing power vaccuum eventually fell to Macedon under Philip who fought against Persia, only for his son, Alexander the III, to take up the true victory in rulership over both Greece and Persia. The Pelopponesian War ultimately led to the future establishment of the Hellenic world under Alexander the Great, though it never would again achieve its former greatness in artistic and philosophic inquiry.