 In 88 BC , an aristocratic senator named Lucius Cornelius Sulla was elected Consul , and soon left for a war in the east . When a Tribune revoked Sulla 's command of the war , Sulla brought his army back to Italy , marched on Rome , secured the city , and left for the east again . In 83 BC he returned to Rome , and captured the city a second time . In 82 BC , he made himself Dictator , and then used his status as Dictator to pass a series of constitutional reforms that were intended to strengthen the senate . In 80 BC he resigned his Dictatorship , and by 78 BC he was dead . While he thought that he had firmly established aristocratic rule , his own career had illustrated the fatal weakness in the constitution : that it was the army , and not the senate , which dictated the fortunes of the state . In 70 BC , the generals Pompey Magnus and Marcus Licinius Crassus were both elected Consul , and quickly dismantled Sulla 's constitution . In 62 BC Pompey returned to Rome from battle in the east , and soon entered into an agreement with Julius Caesar . Caesar and Pompey , along with Crassus , established a private agreement , known as the First Triumvirate . Under the agreement , Pompey 's arrangements were to be ratified , Crassus was to be promised a future Consulship , and Caesar was to be promised the Consulship in 59 BC , and then the governorship of Gaul ( modern France ) immediately afterwards . In 54 BC , violence began sweeping the city , and in 53 BC Crassus was killed . In January 49 BC , the senate passed a resolution which declared that if Caesar did not lay down his arms by July of that year , he would be considered an enemy of the republic . In response , Caesar quickly crossed the Rubicon with his veteran army , and marched towards Rome . Caesar 's rapid advance forced Pompey , the Consuls and the senate to abandon Rome for Greece , and allowed Caesar to enter the city unopposed . 
