This is the third and final volume (Vol. I 1991, Vol. II 1996) of a historical and literary commentary on the history of the first 20 years of the twenty-seven-year 'Peloponnesian War' (between the Athenians and Spartans and their respective allies) written by the great fifth-century BC historian Thucydides. The present volume of commentary covers the ten closely-narrated years 421-411 BC, and nearly half of the total of eight 'books' (subdivisions) of Thucydides' work. It includes one of the most famous sections of ancient Greek literary writing, the lengthy and supremely dramatic account of the disastrous Athenian expedition against Sicily (415-413) in Books 6 and 7; but also the Melian Dialogue (Book 5), a notorious document of Athenian imperialism; and the account of the oligarchic revolution at Athens in 411 (Book 8). All Greek is translated. There is a thematic General Introduction and two Appendixes.