Summarizing the Third Century Crisis

[L C Cinna]

Well well well...3rd century crisis, my fav topic...so much to write, so little time.

Just on a short note:

Like someone already said, it doesn't seem like Gallienus much inreased the number of cavalry. He simply concentrated a lot of the cavalry forces available and regrouped them. Looking at the beginning of his reign until about 262 he's constantly on the march from one area of crisis to the next. there are also indications from extensive movement of legionary detachments throughout the empire, but especially concentrating on the Rhine and Danube. After his victories against the Alemanni and Franks he moved to the Danube which was hard pressed at that time (archeology has shown several traces of destruction in the area of Hungary for example: see Fitz, Jenö: Ingenuus et Regalien: Latomus 1966).

He usually took a core army with him wherever he went, consisting of vexillations and cavalry (the cavalry being one of the main elements as the bigger number of infantry were added at the place of the conflict).

Detachements of I Minervia appear in the Danubian area between his reign and the 270ies/80ies (the 2 stones are not exactly datable yet). Probably they went there with him as at the same time british troops appear along the Rhine in higher numbers, probably brought there to refill the gaps caused when he took troops to fight Ingenuus and Regalianus at the Danube.

Milan was an important base but i think it'd be too much to see it as THE base for his new "cavalry army" as has been suggested before by some scholars. It was indeed an important strategic position after the loss of the Gallic Empire to Postumus (including Raetia which secured the entrance into Italy) but it should rather be seen as a stronghold from which he could operate towards the Danubian frontier (although things had become a bit more quiet there, especially after a contract with the Marcomanni who now guarded parts of the northern danubian boarder) should problems occure, on the other hand protect Italy as well from Postumus. Milan was probably his base of operations when he prepared to retake the Alpine passes and Raetia (which he managed to do) and for his unfortunate attack into Gallia. At the same time however, he seems to have a 2nd "field army" operating on the lower Danube for most of his reign. This already starts in 260 when, after defeating Ingenuus, Gallienus returns to Italy to fight the Alemannic incursion (units which seem certain in joining him there are parts of Pathica and the Praetorians) while Aureolus (the guy often refered to as his cavalry commander) operates along the lower Danube and Thrace. Aureolus must have had a considerable force under his command with the mission to restrenghten the areas which had rebelled under Ingenuus, leading the defeated Ingenian troops back and defeating the Macriani (who had lead a big part of the army Valerian had used for his war against the Persians into Greece). After defeating the Alemanni Gallienus turns towards the Danube again to pacify the area and keep the Sarmatians away.

So we have at least 2 fully operational field armies in this area between 259 and 262. He didn't create a single cavalry force but rather collected as much cavalry as possible, gave those forces a nominal basis at Mediolanum where they could meet up to regroup in times of peace and split those cavalry forces (and several selected vexillations) to form field armies which would march quickly to an area of conflict, join the local infantry forces and form an effective army.

There's also that one thing I came across several times in different history books, namely that in 268 when Aureolus rebelled in Milan, he was commander of the cavalry (which he really seems to have been nominally) and that it was the "new cavalry army" rebelling. This seems not very likely imho as Gallienus was leading a major war against the Goths at that time (final victory at Naissus) and it is very unlikely that he left the majority of his newly formed (and freely available) forces which had accompanied him so far at home. Aureolus was probably left there with a much smaller mixed army to guard Italy and Raetia in the absence of the Emperor, that's why he didn't offer battle when Gallienus arrived (besides that Gallienus must have been a very very able commander being never beaten in battle [although he had once to reatreat from Gaul after being severly injured by an arrow]). instead Aureolus joined Postumus and asked him for help, which he never sent.

I'll go into more detail when I have more time...