Imperium
After the last king had been expelled, 2 Roman consuls were elected
every year by the comitia
centuriata. These men were equal in power, in such a way that the
one consul could undo what the other had ordered.
This constitutional power was called imperium.
In the city the consuls would wear a purple-bordered toga (toga
pretexta) and sat on a folding chair adorned with ivory (sella curulis).
Calendar
The Roman
calendar was based upon these consuls: The years were not numbered but indicated as the year of
the consuls X and Y. For this the names of the consuls had to be
registered in a sort of list (Fasti), the contents of which are available here.
Commanders
The Roman consuls mainly acted as military commanders.
It was the senate that told them who had to go where with his army and provided the funds. Consul was the highest
rank in the Roman
society.
Life and death
In public the Roman consuls were preceded by 12 lictors, each of whom carried
a fascis. Fasces were bundles of metal rods tied together with a
red thong.
When outside Rome there was put an axe in the middle of the bundle. But see Dionysius of Halicarnassus
The rods symbolized the power of punishment of flogging and the
axe the power to the death penalty to be imposed by the Roman consuls.
Livius (8.7):
Where consul T. Manlius has his own son beheaded for disobedience.
In the city
This implies that within the city the Roman consuls had no ultimate power
over life
and death. Indeed this power came ultimately to the
people of Rome.
Livius: (2.29)(After
the discontent plebs refused to be levied for the army, which was a crime, the same people would acquit the offenders, if the consul would condemn them)
10 years
As a rule a Roman consul could not be elected again within the next ten years. In times
of crisis this rule was often ignored, because obviously an experienced
commander in chief was needed. When the crisis was very deep one of the
consuls could appoint a dictator.
The senate could order the consuls to appoint a dictator, but the decision remained theirs.
In the late republic the senate could appoint a dictator herself.
Proconsul
When the wars became more complicated and further from home, the Romans needed sometimes more than two consuls. In those cases they appointed one or more proconsuls. These men received the same imperium (power) as a consul but only in the area where they were supposed to operate.
In the imperial period the office of consul was not abolished, but the real power of course, was in the hands of the emperor.