The Roman Republic was initially ruled by two annually elected consuls who shared executive power. The Senate, composed of noble families, acted as lawmakers and advisors. The Assembly, made up of plebeian citizens, could vote on laws but had limited power. This system established principles of representative government and separation of powers. However, the Republic gradually moved towards dictatorship under Sulla and then a triumvirate formed by Caesar, Pompey, and Crassus dominated politics. After the deaths of Sulla and Crassus, the rivalry between Caesar and Pompey led to civil war, from which Caesar emerged as dictator with imperial power, ending the Republic.