During the late Roman Republic, there was no modern technology, so propoganda spread via letters. The word "propoganda" itself originally meant the "promotion of true faith"- "congregatio de propoganda fide", but the definition gradually changed to deceit. It became a "mechanism by which ideas are desseminated on a large scale", and was "organised effort to spread a particular belief or doctrine". Propoganda was widely used in the 20th century by dictators and all uses and techniques of propoganda mainly came from the Roman age.
There were a few ways in which Julius Caesar used to spread propoganda while he was away in Gaul fighting the Gallic wars. Firstly, he had representatives in Rome to ensure that he would not be forgotten by the Senate or the people. Secondly, he had a personal correspondent in Rome who would express and deliver his opinions. The correspondent was also responsible for delivering information from Rome to Caesar. Julius Caesar received all the information from Rome- "omnia minima maxima"- and also sent lots of letters to Rome. Thirdly, Caesar was a prolific writer and produced a myriad amount of literary works- most notably the commentaries on the Gallic Wars- and these works all protray Caesar as an audacious yet also clementine general. This protrayal of a general adhered to all the qualities Roman people looked up to. Fourthly, Caesar also tried to influence other writers to produce works praising him. For example, Varro Atacinus's Epic and Cicero's speeches all praised Caesar's "great virtues". Fifthly, Caesar also made use of spectacles and other imagery- his lavishness in staging games all attempted to pacify the Romans in a time of chaos. Coins were also minted commemorating the general's virtues.
Caesar was extremely successful in his propoganda efforts, and really tried to paint the picture of a clementia Caesaris (clementine Caesar) and a person who deeply knew the troubles of the populus Romanus (people of Rome). Caesar protrayed himself as a general who spared the lives of opponents through dessemination of coins showing Caesar showing sympathy. HE also re-ereted the statue of Gaius Marius, knowing the populace liked him. A saeptia Iulia was built to give the populace a proper place to vote, and coins were circulated that represent the Tribunician bench and libertas.