Crisis of the 3rd Century&Growing Dangers of Trade

[Robert Vermaat]

Regarding "booty"...I have read that it was often the only real "take home" pay soldiers received, especially in times of crisis. Not all usurpation were caused by"greed"; many were due to the inability of the central government to timely respond to external threats. ..."self help" so to speak.

Agreed. In this case I doubt that Postumus was greedy. it was Gallieneus' son Saloninus who demanded all the booty for himself. No doubt Postumus was 'caught between a rock and a hard place', being confronted with troops on the edge of mutiny. Either he planned to take the throne and saw the opportunity, or he had to choose between a mutinous army and a disrecpectful commander.
In my opinion he was probably not the calculating usurper but a disgruntled local who saw the wealth of the province bleding away without the necessary safekeeping in return. The usurpation was a big change to the region, which turned away from Italy to look at NorthWest affairs first - the focus shifted. In fact this change foreshadowed, i think, the later Frankish Empire, and turned Italy into a side affair.