This paper examines how the battle exhortation was analysed in ancient rhetoric. The Thucydidean battle exhortation is the key: by combining different lines of argumentation drawn from the oratorical practices of the late fifth century bce, Thucydides created a new kind of battle speech. The main feature of this speech is its flexibility in reasoning and its ability to fulfil new functions in historiographic works. Those two features explain why that kind of military speech proved so successful with later historians, and they also explain the views of imperial-age rhetoricians in analysing these speeches.