Titus Livius (Livy), The History of Rome, Book 22
D. Spillan, A.M., M.D., Cyrus Evans, Ed.

8. Before their plans were sufficiently determined another unexpected defeat is reported: four thousand horse, sent under the conduct of C. Centenius, proprietor, by Servilius to his colleague, were cut off by Hannibal in Umbria, to which place, on hearing of the battle at Trasimenus, they had turned their course. The report of this event variously affected the people. [2] Some, having their minds pre-occupied with heavier grief, considered the recent loss of cavalry trifling, in comparison with their former losses; [3] others did not estimate what had occurred by itself, but considered that, as in a body already labouring under disease, a slight cause [p. 775]would be felt more violently than a more powerful one in a robust constitution; [4] so whatever adverse event befell the state in its then sickly and impaired condition, ought to be estimated, not by the magnitude of the event itself, but with reference to its exhausted strength, which could endure nothing that could oppress it. [5] The state therefore took refuge in a remedy for a long time before neither wanted nor employed, the appointment of a dictator; and because the consul was absent, by whom alone it appeared he could be nominated; and because neither message nor letter could easily be sent to him through the country occupied by Punic troops; [6] and because the people could not appoint a dictator, which had never been done to that day, the people created Quintus Fabius Maximus pro-dictator, and Marcus Minucius Rufus master of the horse. [7] To them the senate assigned the task of strengthening the walls and towers of the city; of placing guards in such quarters as seemed good, and breaking down the bridges of the river, considering that they must now fight at home in defence of their city, since they were unable to protect Italy.