<P> After leaving office, the consuls were assigned by the Senate to a province to administer as governor . The provinces to which each consul was assigned were drawn by lot and determined before the end of his consulship . Transferring his consular imperium to proconsular Imperium, the consul would become a proconsul and governor of one (or several) of Rome's many provinces . As a proconsul, his imperium was limited to only a specified province and not the entire Republic . Any exercise of proconsular imperium in any other province was illegal . Also, a proconsul was not allowed to leave his province before his term was complete or before the arrival of his successor . Exceptions were given only on special permission of the Senate . Most terms as governor lasted between one and five years . </P> <P> In times of crisis, when Rome's territory was in immediate danger, a dictator was appointed by the consuls for a period of no more than six months, after the proposition of the Senate . While the dictator held office, the imperium of the consuls was subordinate to the dictator . </P> <P> After Augustus became the first Roman emperor in 27 BC with the establishment of the principate, the consuls lost most of their powers and responsibilities under the Roman Empire . Though still officially the highest office of the state, with the emperor's superior imperium they were merely a symbol of Rome's republican heritage . One of the two consular positions was often occupied by emperors themselves and eventually became reserved solely for the Emperor . However, the imperial consuls still maintained the right to preside at meetings of the Senate, exercising this right at the pleasure of the Emperor . They partially administered justice in extraordinary cases, and presented games in the Circus Maximus and all public solemnities in honor of the Emperor at their own expense . After the expiration of their offices, the ex-consuls (proconsuls) went on to govern one of the provinces that were administered by the Senate . They usually served terms of three to five years . </P> <P> Roman dates were customarily kept according to the names of the two consuls who took office that year, much like a regnal year in a monarchy . For instance, the year 59 BC in the modern calendar was called by the Romans "the consulship of Caesar and Bibulus", since the two colleagues in the consulship were Gaius Julius Caesar and Marcus Calpurnius Bibulus--although Caesar dominated the consulship so thoroughly that year that it was jokingly referred to as "the consulship of Julius and Caesar". The date the consuls took office varied: from 222 BC to 153 BC they took office 15 March, and from 153 BC onwards it was on 1 January . The practice of dating years ab urbe condita (from the supposed foundation date of Rome) was less frequently used . </P>

The two orders of roman society were known as the