After changes to Roman army driven by the
Social War (91–87 BC) and subsequent
civil wars (further formalised by the emperor
Claudius), a professionalized military system was created, in which legions were commanded by a legionary legate (
legatus). Six tribunes were still posted to a legion, but their duties and responsibilities had changed, becoming more a political position than a military rank. The second-in-command to the legate was the
tribunus laticlavius or 'broad-stripe' tribune (named after the width of the stripe used to demarcate him on his tunic and toga), usually a young man of senatorial rank. He was given this position to learn and watch the actions of the legate. They often found themselves leading their unit in the absence of a legate, and some legions were permanently commanded by a broad-stripe tribune, such as those stationed in Egypt, as an
Augustan law required that no member of the Senatorial Order ever enter Egypt. In contrast to the broad-stripe tribune, the other five 'thin stripe' tribunes were lower in rank, and were called the
tribuni angusticlavii. These 'officer cadets' According to
Tacitus, they did not always take their appointment as seriously as they might, contrasting Agricola's tribuneship to his peers by saying "[Agricola did not], like many young men who convert military service into wanton pastime, avail himself licentiously or slothfully of his tribunitial title, or use his inexperience to spend his time in pleasures and absences from duty". ==Principate==