How did Thucydides influence Roman historians such as Livy and Tacitus?

Thucydides, the preeminent Greek historian, profoundly influenced Roman historiography, particularly through his focus on political and moral analysis, the use of speeches to reveal character and motive, and a commitment to interpreting the human condition in times of conflict.123

While Livy and Tacitus approached history with different priorities, Thucydides’ legacy was mediated significantly through the Roman historian Sallust. Sallust explicitly adopted Thucydides as his stylistic and intellectual model, attempting to replicate the Greek historian's dense, austere prose and his method of using speeches to ascribe motives and analyze the moral decay of political power.45

Tacitus, in turn, developed this "Sallustian style" to an extreme, incorporating archaic and poetic language to create his signature ironical and dramatic narrative. Like Thucydides, Tacitus utilized history as a tool for sharp political analysis, though he focused specifically on the corruption inherent in dynastic power and the decline of political freedom under the Roman Empire. Livy, while less focused on Thucydidean political rigor, shared the broader ancient commitment to using history as a moral record, employing eloquent speeches to bring the past to life and provide warnings for his contemporaries.465