Proconsul, one who under the Republic was sent by the consuls to govern a province; for which purpose he was invested with powers almost as extraordinary as those which appertained to the consulship itself.- Names of proconsuls and propraetors were stamped on coins of Roman families under the authority of the senate.  Thus we see on denarii of the Annia, Appuleia, Caecilia, Junia, Manlia, and Scribonia families, the EX SC added to the title of PROCOS, together sometimes with the names of the provinces whose affairs those magisterial delegates administered, as in the case of Sicily.

The Proconsul governed the province to which he was appointed, according to the Roman Laws.  The year of the proconsulate dated its commencement from the time that this magistrate made his official entry upon his provincial government.  At the expiration of the year, he resigned his charge, which included the command of the soldiers, into the hands of his successor, if arrived, and in thirty days quit the province.  If the successor was not yet arrived, the proconsul left his lieutenant to act during the interval, and on his return to Rome rendered an account of his administration to the senate.- These magistrates enjoyed in their respective provinces the same honours as the consuls did at Rome.  All proconsuls of provinces were called rectors or presidents of the Roman people; they were attended on state occasions by twelve lictors, armed with fasces and axes, if they had served the consulate; otherwise by six only.  The heads of proconsuls were not, as a matter of custom, engraven on coins; but their titles were recorded on the products of the mint, and they are represented, in quadriga, bearing the ivory sceptre, as the symbol of proconsular government, on coins of the Servillia, Sextia, and Sosia families.

Under the empire the proconsulate was preserved: and with the stronger reason for its continuance that as the dominion of Rome increased in extent, it became requisite to multiply the number of officers, invested with sounding titles and armed with the fullest authority, for the government of territories at a instance, more or less remote, from the great center of supreme power.  From the period when Augustus divided the administration of the empire between himself and the senate, the latter sent to those provinces which had been conceded by the Emperor to their care, governors, who under the names of proconsuls or propraetors, administered justice there; but these senatorial representatives held no military command, nor any control over the revenue, both which were exclusively confined to the sovereign's officers.-"Under the Emperors (says Eckhel) the proconsular dignity soon became perpetual in their persons, or in those of their destined successors.  By authority of the senate, Claudius decreed that Nero Caesar should possess proconsular power (extra urbem) out of the jurisdiction of the city.  Antoninus Pius was made by Hadrian, at one and the same time, his colleague in proconsular government and in the tribunitian power.  And a similar privilege was conferred, in his turn, by Antoninus Pius on his adopted son Marcus Aurelius."

"There were, therefore, (adds the same writer), three kinds of proconsulates among the Romans; of these the first were the ordinary ones, who went out to govern provinces, having acquired the office either by lot, or by agreement, or subsequently by the mission of the prince himself.  The second was an extraordinary proconsulship, to which, for a certain period of time, greater power, than usually belonged to proconsuls, and extending over more provinces, was entrusted.  The third was perpetual, and its authority prevailed throughout all the provinces; and this, therefore, was decreed by Augustus to all Emperors, and by them frequently to the Caesars, and to the destined successors to the throne" Vol vii 340

The proconsulate of the Augusti and Caesars is seldom read on the monumental inscriptions of antiquity, either on marble or brass.  Of such coins, still fewer in number, as add the title of proconsul to that of the emperor, the following list is furnished by Eckhel:

CONSVL IIII P P PROCOS in others CONSVL VII P P PROCOS on coins of Diocletian.

COS III P P PROCOS on others CONSVUL IIII - VI - VII -VIII - P P PROCOS on coins of Maximian Hercules

CONSVL V P P PROCOS on coins of Constantius Chlorus

CONSVL P P PROCONSVL on coins of Licinius senior

CONSVL P P PROCONSVL - P M TRIB P COS IIII P P PRO COS - P M TRIB P COS VI P P PROCOS on the coins of Constantine the Great