Chapter 6 : Ancient Rome and Early Christianity Rome's powerful army protected the republic and expanded its territory. Military conquests brought wealth to Rome. On large estates, slave labor replaced small, independent citizen-farmers. This and other factors led to civil war and an increased political role for the army. In 45 B.C. Julius Caesar set up a dictatorship. After his assassination, his nephew Octavian became Augustus, the first Roman emperor. During the Pax Romana, a long period of peace and prosperity, the Romans developed a system of laws and built roads, aqueducts, and public buildings. Great literary figures of this time included poets Horace and Virgil and historians Livy and Tacitus. The period also marked the birth of Christianity. The western empire fell amid political chaos, economic crisis, and Germanic invasions. Only the eastern part of the empire survived.