The coastal belt of the Eastern shores of the Adriatic was fully integrated into the Roman system in 59 B.C. as a consequence of the intensive political conflict between Gaius Julius Caesar and the Senate led by Marcus Porcius Cato. With the enactment of Vatinius’ law in the Popular Assembly, the province of Illyricum was officially created and, along with Cisalpine Gaul, handed off to its first governor, Gaius Julius Caesar. For the duration of his five-year mandate in the region, Caesar had intended to begin his conquests toward the Danube area. However, soon after Vatinius’ law and due to the migration of the Helvetians, the seemingly calm province of Transalpine Gaul came under threat. Prompted by the experience of similar situations in the past, the Senate gave Transalpine Gaul to Caesar who set off, as it turned out, on a long-term conquest of all of Gaul. Available literary data demonstrate that the territory of the newly founded province of Illyricum was not created all at once, but was the result of a long-term process which expanded the Roman protectorate, an area comprised of protected communities and cities. Beginning with the first Roman military intervention on the Eastern shores of the Adriatic during the First Illyrian War, the protectorate further on increased due to Roman military successes and territorial acquisitions. The downfall of the Illyrian and Macedonian kingdoms in 168/167 B.C. added a wide coastal area from the Neretva River in the northwest to the borders of Epirus in the southwest. However, the protectorate was divided in 146 B.C. The areas south of Lissus were incorporated into the province of Macedonia, while the northwest remained as a separate, periodically-expanded whole until the enactment of Vatinius’ law. It is thus that the structure of the future province of Illyricum was created. More specifically, due to commanders’ decisions on territorial organization after the successful completion of every military campaign which, in time, created the legal and administrative framework which would enable the governor, once he appeared, to govern his province. With Anicius’ proclamation, the former Illyrian kingdom was divided into three parts, before which the Histri fell under Roman rule. The pressure of the Delmatae on the coastal area of central Dalmatia was repressed with a number of separate decisions and, as punishment, the Ardiaeans were moved to into the interior. After Tuditanus’ campaign, the territories of Liburnians and Iapodians were incorporated into the existing protectorate and Roman rule was united all along the Eastern shore of the Adriatic. Therefore, at the moment Caesar was appointed governor of Illyricum, for every area of the province there already existed a series of successive decisions that defined the relationship between communities, their position in the province, their obligations toward Rome and, for some, the afforded privileges. That affected the organizational and administrational aspect of the province a great deal. Illyricum, when Caesar received it, was divided into five regions, named after the most important community that lived within its borders – Histria, Liburnia, Iapodia, Dalmatia and old Illyricum. These regions were defined by inter-provincial borders and existing contracts with Rome, while the most southern (old Illyricum) was administratively organized. With the formation of a judicial conventus in Narona after the campaign of Servius Fulvius Flaccus in 135 B.C., a centre with jurisdiction over more than 89 communities was created. This was noticed and recorded, fifty years later, by Marcus Terentius Varro. An administrative division of the region of old Illyricum was thus carried out, and it remained until Caesar’s time and, even later, served as a model for the division of the province of Dalmatia. All of that constituted the Illyricum which was given to Caesar to rule over. As a dynamic province, it did not differ greatly from others in the Roman realm. It was territorially defined and had its own leges provinciae. Additionally, there was regional organization and an administrative framework for at least one part. Although Caesar did not pay much attention to events in the province during his rule, once started, the process of Romanization and the transformation of the territory into a fully administratively-settled province went its own course. More and more Roman citizens arrived on the shores of Illyrium and began to organize themselves in convents of Roman citizens (conventus civium Romanorum). Their influence and strength for the autochthonous population eventually meant the loss of their previous position. Consequently, Illyricum became a real Roman province with great strategic importance, a fact which became all the more evident upon the breakout of the civil war between Caesar and Pompey when the period of so called “Caesars’s Illyricum” officially ended.