Mobile Field Armies

[Lothia]

Ave, Civitas,

I am working on a series of novels set during the Later Roman Empire.

I noticed that the Eastern Empire had Magister Militum Praesentalis I, and II, two mobile field armies.

However, the Western Empire does not seem to have equivalent organizations.

Since they were once a single empire, can someone explain why, when they split, there are differences in defense and offense between the two halves of the empire?

Again, thanks in advance for your help.

[Robert Vermaat]

Ave, Civitas,

I am working on a series of novels set during the Later Roman Empire.

I noticed that the Eastern Empire had Magister Militum Praesentalis I, and II, two mobile field armies.

However, the Western Empire does not seem to have equivalent organizations.

Since they were once a single empire, can someone explain why, when they split, there are differences in defense and offense between the two halves of the empire?

Again, thanks in advance for your help.

Really no idea, it also seems to depend on what period you are looking at: the situation around AD 300 differed from AD 400.  

The West had magistri peditum and magistri equitum were appointed for every praetorian prefecture but later these were either 'devolved' into simple regional commanders styled 'magistri militum', while the main function was combined into one title of magister utriusque militiae. who became the power behind the throne. Of course there were more ‘mobile armies’ in the West too.

Maybe that is the main difference – the Emperors in the East managed to retain that power. Maybe that’s why in the East, there were two senior generals, who were each appointed to the office of magister militum praesentalis. Or maybe they were meant to counterbalance each other?

Mind you, maybe it's a lack of sources that present us this picture?

[Lothia]

Thank you Robert.

So, it seems as though of the field armies in the East the magister militum praesentalis I and II were senior and equal. That helps a lot.

Tom