Much maligned Roman senator who tied his political fortunes to the cause of Caesar & his successors. As a trusted ally of Julius Caesar in his feud with Pompey, Lucius Munatius Plancus was left as proconsul of all the newly conquered territory in Gaul when Caesar returned to Rome (45 BCE). There he founded the colony of Lugdunum [modern Lyon, France]. Following Caesar's assassination (44 BCE), he became a supporter of Marc Antony & served as co-consul with Lepidus in the early days of the new triumvirate (42 BCE). While Antony was occupied with securing the eastern provinces, he twice made Plancus his proconsul, first of Asia Minor (40 BCE) & then of Syria (35 BCE). Following Antony's defeat by the Parthians (33 BCE), however, Plancus allied himself with Octavian. As Octavian reorganized the political institutions of the republic into those of an empire, it was Plancus who persuaded him to adopt the name Augustus ("reverend") rather than a title with monarchical connotations (27 BCE).  He contributed to Augustus' reconstruction of Rome by restoring the temple of Saturn. A more dubious distinction is that after Plancus' term as censor (22 BCE), Augustus decided to abolish that office left over from the old republic.

Plancus is often cited as an opportunist who switched his political allegiances to secure & advance his own fortunes. While that charge may be justly leveled at many Romans in the political turmoil that characterized the civil wars, it is an unfair assessment of a man whose loyalty, ability & advice was obviously long trusted by the three men who molded the new Roman imperial order. Plancus was not the only supporter Antony to defect to Octavian. This is better blamed on Antony's own increasing recklessness & abandonment of the traditional Roman values that Octavian wisely championed rather than on the political fickleness of their supporters.

References: Cassius Dio, Roman History 40.55; 48.26; 50.3; 54.1.
                   Suetonius, Twelve Caesars: Augustus 29.
                   Velleius Paterculus, Roman History 2.83.

Other resources on line:

• Lucius Munatius Plancus - entry in Wikipedia's web.

• Plancus' Mausoleum at Gaeta - image of best preserved tomb of the Augustan era [Lacus Curtius].

• Funerary Inscription of L. Munatius Plancus - Bill Thayer deciphers the plaque mounted above the entrance of the Gaeta tomb [Lacus Curtius].