Military tribunes were officers of the Roman Legions. In the Republican period, there were six appointed to each legion. Authority was given to two at a time, and command rotated between the six. Tribunes were men of Senatorial status appointed by the Senate. To attain the position of tribune, one only needed to be a member of the ruling class--ability did was not taken into account.
After the Marian Reforms made the army professional, legions were commanded by a legionary legate. Six tribunes were still posted to a legion, but their duties and responsibilities had changed. The second in command to the legate was the tribunus laticlavius, a youing man of Senatorial rank. He was given this position to learn and watch the actions of the legate. The other five tribunes were slightly lower in rank, and were called the tribuni augusticlavii. These were men of equestrian rank who had seen some prior military action.
Tribunes in the professional army had no definite duties. They were appointed tasks by the legate whenever the need arose.
