Metellus Scipio in the Battle of Thapsus, after which the Pompeians retreated yet again to Hispania. Caesar then defeated the combined Pompeian forces at the Battle of Munda. With Pompey defeated and order restored, Caesar wanted to achieve undisputed control over the government. The powers which he gave himself were later assumed by his imperial successors. His assumption of these powers decreased the authority of Rome's other political institutions. Caesar held both the dictatorship and the tribunate, and alternated between the consulship and the proconsulship. In 48, Caesar was given permanent tribunician powers. This made his person sacrosanct, gave him the power to veto the senate, and allowed him to dominate the Plebeian Council. In 46, Caesar was given censorial powers, which he used to fill the senate with his own partisans. Caesar then raised the membership of the Senate to 900. This robbed the senatorial aristocracy of its prestige, and made it increasingly subservient to him. While the assemblies continued to meet, he submitted all candidates to them for election, as well as all bills for enactment. Thus, the group became powerless and were unable to oppose him. Caesar's assassination Caesar began to prepare for a war against the Parthian Empire. Since his absence from Rome would limit his ability to install his own consuls, he passed a law that allowed him to appoint all magistrates, and later all consuls and tribunes. This transformed the magistrates from representatives of the people to representatives of the dictator. Caesar was now the primary figure of the Roman state, enforcing and entrenching his powers. His enemies feared that he had ambitions to become an autocratic ruler. Arguing that the Roman Republic was in danger, a group of senators led by Gaius Cassius and Marcus Brutus hatched a conspiracy and assassinated Caesar at a meeting of the Senate on 15 March 44. Most of the conspirators were senators, who had a variety of economic, political, or personal motivations for carrying out the assassination. Many were afraid that Caesar would soon resurrect the monarchy and declare himself king. Others feared loss of property or prestige as Caesar carried out his land reforms in favor of the landless classes. Virtually all the conspirators fled the city after Caesar's death in fear of retaliation. Second Triumvirate The civil wars that followed destroyed what was left of the Republic. After the assassination, Caesar's three most important associates,