More treason trials followed. Tacitus writes that Tiberius had been hesitant to act at the start of his reign, but now, towards the end of his life, he seemed to do so without compunction. However, Tacitus' portrayal of a tyrannical, vengeful emperor has been challenged by several modern historians. The prominent ancient historian Edward Togo Salmon notes in his work, "A history of the Roman world from 30 B.C. to A.D. 138":