The year is 46 BC, the civil war is still going on in Rome, although Pompey Magnus is defeated and dead, theoptimates are still not completely defeated. During this time, Publius Sulpicius Rufus, Caesar's legate and commander, arrives in Illyricum. The only source that mentions Sulpicius' army in Illyricum is the letter of Marcus Tullius Cicero, which he sends to Rufus. From the letter we do not learn much about Sulpicius' tasks in Illyricum, but we can nevertheless extract some information important for understanding the mission to Illyricum. A year later, Publius Vatinius was sent to Illyricum as proconsul. His proconsulship is more thoroughly and extensively documented for us, both in letters and in other sources. However, his campaign is no less susceptible to questioning and confusion created by the vague information in Cicero's correspondence with Vatinius. The paper will deal with these two military missions, studying the original data, as well as the previous positions of historiography regarding the causes, course and consequences of the campaigns.