Those Romans Sure Are Popular

Over the last few days, I've read two different books on the Roman military, and each takes a slightly different tack.

The Grand Strategy of the Roman Empire, from First Century A.D. to the Third, Edward Luttwak - Luttwak focuses on the Roman's military strategy, and troop deployments from around the time of the Illycium revolt of A.D. (which halted Augustus' advancement into Bohemia, because he had to put down said revolt first) up to the rule of Constantine. He describes three different strategies over that time, and goes into the mechanics of them, what defenses would be constructed, how troops would be divided up between cavalry or infantry, the reasons behind employing those strategies, as well as their weaknesses.

Personally, the client state strategy of what he calls the Julio-Claudian era sounds the most efficient to me. In that system, there are states/kingdoms on the edge of official Roman territory. These areas aren't strictly under Roman control, but they're on positive enough terms that the Romans don't feel it necessary to send legions to crush them. But the Romans could do that, and the client states know it, which is why they go along with it. Plus the client states will act as a buffer between the Romans' territory and any threats from outside their zone of control. If the client states can handle the threat themselves, great. If not, by the time they're overrun, the Romans probably have time to move some legions to their border and halt the enemy advance. It's not a great system for the client state, but they maintain some limited suzerainty (Luttwak is very fond of that word), and in theory they can work up an arrangement where the Romans will help them if they need (because it would be in Rome's best interests to keep a friendly group on the border, rather than some new hostile conquering bunch). This method requires a lot of diplomacy, but it's a pretty efficient way to use the military since the mere threat of them serves as a deterrent to most (and you can always grease some palms to ease their wounded pride), leaving them free to concentrate more fully on the folks who won't play ball, say the Parthians. Plus, it lowers the chances the Romans have to fight in their own lands, which is the sort of thing the populace appreciates.

Luttwak goes from there to the Antonine system, where the client states are largely annexed (and the ones that aren't are so weak as to be useless as buffers). At this the armed forces are everywhere, because there are no more buffers between Roman territory and potential enemies, so you can't concentrate a large portion of your forces in just one trouble spot. Still, Luttwak points out that simply spreading your forces evenly along a wide perimeter isn't a great strategy except in certain circumstances. So he goes into a discussion of the Roman use of limited walls (Hadrian's Wall, for example), which were not heavily staffed, but would provide some early warning of impending large-scale attack, and could conceivably handle smaller raids on their own. The legions would be stationed father in the empire, ready to move to a specific location as necessary (which is where all those nice roads come in handy).

There's a lot more, but I'll leave it for you to read. My warning is that Luttwak was apparently a modern military systems analyst, and depending on your tolerance for it, he can bury you under specific legion names, sites of conflict that are called very different names now (and he doesn't always provide those names, so I'm not always clear where things are happening in relation to each other), and at times, a lot of numbers on how many legions were where, and how many people that constituted, and how many of those were infantry and so on. Still, the discussion of elastic defense versus defense in depth, both of which the Romans used later on, and the advantages and disadvantages of a centralized field army were highly interesting.

The book does raise one other point, and maybe this is a common issue for historians. In attempting to explain why the Romans might adopt a certain tactic, Luttwak assumes they were thinking rationally, and investigates the problem accordingly, so that ultimately he ends sections with a statement to the effect of how it's obvious why they did x, y, z. Except it's not as if all the Roman leaders were tactical geniuses, or if what they say about Caligula is true, even sane, so I wonder if rational thinking actually determined the plan of action. Luttwak makes a convincing enough case that I tend to agree with him, and I suppose it's more satisfying to feel you can understand the logic behind something, rather than throwing up your hands and declaring the perpetrator off their rocker, it was just a thought I had.

Arther Ferrill's The Fall of the Roman Empire: The Military Explanation is what the title suggests. Have to hand it to these historians, they don't seem fond of misleading titles. Ferrill's book is a bit shorter, and with a lot more pictures (mostly various artwork of noteworthy people, whereas Luttwak's illustrations were maps of territories or diagrams of defense systems, which I found more useful), and actually offers an explanation for the fall of the Roman Empire, which Luttwak doesn't concern himself with. Ferrill starts around the time of Hadrian (after a chapter discussing past historians' views on the Romans), and goes up to 476 A.D., so there's only limited temporal overlap between the two books. Ferrill uses considerably less technical jargon, so in that sense, it's easier to follow. His feeling is that the western Roman Empire fell because their military declined, losing its trademark discipline, due to the increasing addition of barbarians to their ranks. The barbarians followed their own commanders, who weren't following Roman tactics or drills, so the Romans didn't see why they ought to have to drill, so they lost that discipline that helped them maintain composure even if a battle might be going poorly at a given moment. Ferrill seems to pin a lot of this on a Stilicho, who followed Theodosius' plan of compromise with the barbarians, trying to integrate them into the empire. Also, for various reasons Stilicho failed on roughly four occasions to destroy the Visgoth leader Alaric, which Ferrill argues lowered the morale of the Roman forces. Then, when Honorius wouldn't even send them out to try and defend Rome from 407-410, they were irrevocably wrecked, and fell apart.

I don't know. Certainly discipline was a key to the Roman infantry success, and so if they lose discipline, but use the same tactics that demand it, things are going to go poorly. I can't shake the feeling that Romans had too many enemies, and discipline or no, at that point, they couldn't defend themselves from every direction at once. I'd tend to point more at all the instability at the leadership positions myself, with different commanders proclaiming themselves in charge, then using their legions to fight other legions run by other commanders who made the same claim. It seems like that would damage the unity of your forces, when they never know if tomorrow they'll be fighting other Romans because their commanders are squabbling. Maybe that's just another way discipline breaks down.

It's interesting that both authors take shots at various historians. Luttwak isn't fond of what he perceives as a Clausewitzian bias against defensive systems, a bias which apparently feels if a defense can defend against everything, it's useless. This is the charge leveled at the walls the Romans erected, since they certainly couldn't stop large-scale invasions. As I mentioned, Luttwak argues they aren't supposed to do that, but serve as an early warning against those (and a deterrent against smaller incursions), so the larger military forces can be brought up before the enemy reaches important urban or agricultural locales. Ferrill on the other hand, seems mostly contemptuous of historians that argue that barbarians weren't so bad, that they absorbed enough Roman ideas that they helped carry the way of the Roman Empire forward, so they didn't really bring about a Dark Age. Ferrill really has nothing nice to say about the barbarians at all, unless you consider a statement that once the Roman legions lost their discipline, their tactics were worse than the various Germanic tribes a compliment.

He also throws in a jab at Luttwak, whose book predates his by a decade. Except I think he read Luttwak wrong. He describes Luttwak as one who viewed the use of the forts and walls as theoretically flawed defensive system, and that they were better off when they went to the defense-in-depth strategy supported by a large central reserve. Except Luttwak spent a lot of time explaining the logic (as he saw it) behind the use of the walls and forts, and why he believes they eventually switched. He even notes that when defense-in-depth succeeded in driving enemies back, the Romans would switch back to the preclusive defense at the first opportunity. So Luttwak saw their use of defense-in-depth as something they did temporarily, and with good reason, since it allows the invaders more time to run amok, which makes the empire look weaker, both to the people inside (who are losing homes, lives, crops), and outside, who are thinking they can rush in, grab some stuff, and vanish before the legions show up. So I don't know what Ferrill was going on about there.