The Roman Republic struggled with internal problems as it expanded rapidly through conquest. As the gap between rich and poor widened and class tensions rose, populist leaders like the Gracchus brothers attempted reforms but were killed. This instability led to a power struggle between generals like Marius and Sulla and the rise of strongmen like Julius Caesar, who took control as dictator but was assassinated by senators fearful of his power. After Caesar's death, his adopted son Octavian emerged as the first Roman emperor, taking the name Augustus and establishing the Principate, a period of Pax Romana and stability for the vast Roman Empire he ruled.