Hi everyone,
I'm interested in the kinds of defenses and fortifications the Romans would have had in the eastern empire during the between the years 40 B.C. and 9 A.D. I've read of the Romans having a presence in Pannonia, and also having a continued conflict with the Persians(in this case the Parthian Empire). Specifically, I'm wondering what their contact with the peoples at these borders were, how frequently they were forced to defend them, and how they did so. Was their stance offensive, or defensive? Would the Legions have been sent to act preemptively, or hold up at the border to prevent incursion? Did they ever erect fortifications along the lines of the Hadrian or Antonine Walls(or perhaps, for a Greek bent, the supposed Gates of Alexander)? Was it only forts and regular patrols? None of these?
I'm interested as I'm attempting to write a quasi-historical novel set during the time period. One of the characters is both a veteran of the border conflicts, becomes involved in another with a new group of characters as the book progresses. While the events portrayed are not meant to be totally historically accurate(if at all accurate), I'd like my supporting information for the setting, and background, to be as respectful to history as possible. The topic also interests me in-general, I have not read much of incursions into Rome beyond those of the civil wars, the northern rebellions, and the Hunnic invasion much later, so it would be nice to hear if any such concerns/conflicts existed at the time, and how the empire dealt with them at a caligae-on-the-ground level.
There were virtually no incursions during the period you mention. Almost all the activity was Roman-driven, against Pannonia, in Pannonia territory. Early in the 1st c. BCE Rome was encroaching on Dalmatia and Noricum and beginning to get involved in Pannonia. They fought a war with the "Dalmatians" in the 70s BCE, supposedly reaching the Danube (but not staying around). 35 years later, the Dalmatians embarked upon a fairly serious war against Rome, and Pannonia joined in that cause. Rome (under Augustus) won that war and occupied part of Pannonia, around Siscia (Sissek), in response. In 9 BCE that territory and a bit more was lumped together as a province with the Dalmatian territory. 16 years later, in 6/7 CE, the whole area revolted from Roman rule but was after two years put down by Tiberius and Germanicus.
Up until this point there had not been any permanent border forts here (or anywhere else). Roman armies were mobile and were generally busy building when not on campaign. In winter they built semi-permanent camps in strategic spots, or were stationed in nearby cities (for Pannonia, the Roman frontier city of Aquileia was often a spot where legions parked during the winter). The Roman practice of building limes (more permanent defensive positions on the borders) was just getting started in the first century CE, and would not really get into high gear until the reign of Hadrian, when many of the wooden forts were converted to stone "castles" and more formidable walls were constructed (like the famous one).
A LOT of research and archaeological work has been done recently in the Pannonian/Illyrian region; unfortunately, most of it has been published in languages I can speak or even pronounce. Here are some basics for your time period:
Upon the outbreak of the rebellion, there were at least five legions in "Illyricum" (which included Pannonia): the 9th "Hispana," the 13th and 14th "Gemina," the 15th Apollinaris, and the 20th. Legio XX was at Aquileia for at least part of its time. There was some kind of force in the Emona basin, and Emona was itself an Augustan veteran colony, founded perhaps soon after Actium. In the Emona basin, there is recent archaeological evidence that Nauportus was fortified during the reign of Augustus (which is interesting; you can find that in the journal Arheološki vestnik 58, 2007, 219-270, and it seems to be in English!!). Both Emona as a veteran colony and a fortified camp at Nauportus could be interesting story fodder. You might also check out the edited volume called Limes XX. Actas des XX Congreso Intern. de Estudios sobre la Frontera Romana, 2009 (a lot of the articles are in English).
Recently, several legionary camps from the early 1st century CE have been found along the Sava river. From what I can gather, this was little more than survey, but it proves they were there. These were almost certainly not permanent, but just regular ol' castra that the legions built for the night while on the march.
Legio IX Hispana was probably at Siscia, and there had been two legions here left by Augustus in 34 BCE. This would later be a summer camp for Pannonian legions from 14 CE onwards.
The 20th legion was at Burnum (Šuplja Crkvaon the Krka River) and arrived there in 9 CE with Aemilius Lepidus. It left soon after for Germany in the wake of the defeat of Quintillius Varus. Legio XI might have replaced it at Burnum.
There are ongoing excavations at Tilurium (Gardun/Trilj), where it seems Legio VII was camped. There is an important bridge there across the Cetina River. Sanader is the p
Pannonia did not begin to be urbanized in earnest until the reign of Vespasian, and was the last in this sequence (coastal Dalmatia first, then Illyricum, then Noricum, then Pannonia). I believe that by Vespasian, semi-permanent limes fortifications ("cohort forts") were being constructed along the Danube frontier, bringing with them a certain urbanizing impetus.