That much does seem clear (although it's notable that Rome was invaded in the course of the empire, and promptly retaken). With no one speaking Latin (presumably), no GPS system, very limited fuel (see my previous comment) and an enormous empire (depending on what time they were to attack) it's not especially clear that they could do this, though. They'd need to learn what direction it was in without knowing the language (not impossible, I think -- you could perhaps convey the idea to some local, although being sent in the wrong direction would put an end to the whole thing), not get lost on the way (do tanks still have magnetic compasses? but perhaps the sun would be enough to navigate by) and be close enough to get there without running out of fuel.


"These days it seems like sometimes dreams of Italian hyper-gonadism are all a man's got to keep him going." -- CRwM

As I recall, the Germans in World War 2 had problems with medieval fortifications. Their artillery couldn't easily destroy them. Roman fortifications are probably weaker: taller walls with more stress at the base since they're not built to resist cannons, but I think Marine artillery is probably lighter too .

But let's say they can breach the walls and get in. Remember that Rome has a population of a million, about the same as San Francisco today, and there are only 2,000 marines: they're outnumbered 500 to 1 within the city. I think Rome is just Italy in microcosm, the marines can go anywhere they want within Rome, fortify any area within it, but does that mean they actually control Rome? Sure they can make the Palatine Hill into the Green Zone, but what happens when they have to leave it?

Their advantage is distance weapons: do they really want to be patrolling narrow streets and alleyways where you don't know where the next slingshot or arrow or javelin or swordsman is coming from? When they hear someone's holding a "Death to the Americani" meeting on the other side of the city, what if it's a trap and they're going to be ambushed on the way?

Not convinced it's a great tactical idea to take over the city of Rome. "We have immensely destructive and long range weapons. Let's set up in a fire-prone, incredibly densely-populated city of tall rickety buildings where everybody lives jostling elbows with everybody else".

Burning Rome to the ground might be a better idea militarily, but not a great way to win hearts and minds if you want to take over the Empire.
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It is unlikely that the good of a snail should reside in its shell: so is it likely that the good of a man should?

(Though often the legions were harvesting food directly from the fields.  Marines are likely to be less familiar with how to do that.)

In regards to malaria: the marines would have one advantage in that people would know how it was spread.  Whether a modern population or ancient population is more or less susceptible to it is, I think, an open question.

You are correct that a modern strategy wouldn't work, but someone with knowledge of human history would probably fixate on Cortez, which is the closest analogy we can come to.  Could modern marines implement that strategy?  Probably depends on the calibre of the particular commander.
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[ucblockhead is] useless and subhuman

and they have solar power to charge batteries for radios.

Knowing about Hannibal's tactics (and the weaknesses of Roman strategy in general) won't be of too much help, because if they get down to the level where they're trying to win in the way Hannibal won, they're screwed. They have 2000 people. Fabius' strategy (attrition warfare) is the only viable one for the Romans. If the Romans engage in a pitched battle, they will be mowed down. The only thing the Marines have going for them is technological superiority. If their tactics for defeating the Romans ever become anything other than shooting them at a distance >50m, they're hosed. If they don't win quickly, they're hosed. If they ever get down to any sort of melee, the Romans will chop them to bits.

I agree malaria and other infectious diseases are the biggest problem. Modern militaries are used to dealing with malaria and other infectious diseases, but probably only with a supply chain. I was mildly amused to see comments wondering about smallpox, as smallpox wasn't in Rome at the time and military personnel have been vaccinated against it anyway.

The firearms argument, conversely, is generally something to the effect of "People are terrified to encounter long sticks that make extremely loud noises, omit huge puffs of smoke and kill people from a distance." And, as I say, that does make a certain amount of sense -- there's great drama involved, and we can understand how it might appear to be magic. I'm just not convinced that history supports it.


"These days it seems like sometimes dreams of Italian hyper-gonadism are all a man's got to keep him going." -- CRwM