Haltern, on the banks of the river Lippe in Germany, is one of the best-excavated Roman legionary bases. It is also a very important one, because it was occupied only during Rome’s Germanic Wars – between 5 BCE and 9 CE, to be precise. This means that the finds can be dated pretty accurately, which makes Haltern one of the chronological anchors of the archaeology of the Roman army.
One of the most puzzling finds at Haltern was a coin of the Fourth legion Macedonica, now in the Westfälisches Römermuseum. The problem is that to the best of our knowledge, this unit never belonged to the army of the Rhine. It was in Hispania and took part in the Cantabrian wars. Later, it was moved to Germania Superior and stayed in Mainz, but this was not earlier than 41 or 43. This coin is, therefore, simply not supposed to be in Haltern, unless we accept that it was brought from Hispania to the Lippe valley by a soldier serving in one of the Spanish legions that was transferred to the Rhine: I Germanica and V Alaudae. In other words, the presence of a coin of the fourth legion suggests that soldiers of the First or Fifth were at Haltern.