Avete!
"DB" said I should have a look at this discussion. Looks like most everything has been covered pretty well, but maybe I can clarify a couple points.
While the Imperial legions were professionals and better trained and disciplined overall than the armies of the Roman Republic, even the citizen soldiers of the Republic had a reputation for discipline. We're still talking about a period of almost a thousand years, though, so of course there would be changes in equipment and tactics. But a few generalities are no problem.
Vegetius does indeed claim that Romans used thrusting and scorned those who cut with their swords. But we have to bear in mind that he is a relatively late source, and includes a certain amount of opinion and wishful thinking into his treatise. As others have pointed out, some of those swords are excellent cutters and soldiers would certainly use the edge when necessary. Skeletons at Maiden Castle in Britain, for instance, show cut-marks inflicted by Roman attackers. And Polybius says the Macedonians in the 2nd century BC were shocked at how the Roman gladius hispaniensis lopped off arms and heads.
First specific point is that this gladius hispaniensis was indeed adopted from the Spaniards, but it is a rather longer and slimmer blade than we used to think. They ran 25 to 27 inches long by a maximum width (at first) of 2", whereas the late Republican "Mainz" sword--which we USED to think was the hispaniensis--is rarely over 22" long and is generally wider than 2". Both have long points and (often) slightly waisted profiles. You can see a range of Roman swords on my Legio XX site,
http://www.larp.com/legioxx/gladius.html Roman soldiers were definitely well-trained, with weapon practice and sparring being part of their daily routine. It is again Vegetius who tells us they started by attacking a wooden post using double-weight shields and swords. There is nothing to suggest that they ever trained to fight without shields--for any normal combat they'd have their shields with them. The only time they'd lack them would be for something like a street riot, in which case none of their opponents would have shields, either, and their own well-honed aggressiveness would be all they'd need. There is one account of some of Caesar's men being attacked during a parley, and all they could do to fight their way out was draw their daggers and wrap their cloaks around their left arms. To me that implies a strong desire for a shield!
Constant training and flexible formations meant that they could adapt easily to different opponents and situations. That's what the manipular and cohort systems were all about. The men were drilled to work as a team, backing each other up and offering support whenever necessary. The depth of the formation and the spacing between the men could be varied according to circumstances. The use of the pilum (plural pila) followed by a shield-slam and quick thrusts to face and belly was very effective against opponents who used longer weapons. I got to participate in cutting tests by a Dacian falx, and believe me, you REALLY want to nail that guy with a pilum before he gets a chance to swing! Otherwise, get in so close he can't wind up, at which point you can gut him easily because he can't carry a shield.
Guerrilla warfare is always a problem, but the Romans were surprisingly good at countering it. Most tribal opponents actually couldn't keep such activities up very long because the men all had families and farms to attend to. Burning the villages and farms got rid of the problem. Even mounted raiders in North Africa could be tracked down and eliminated by legionary infantry, because all such raiders had to have a base full of baggage and women. Even in daylight, spotting a couple cohorts a few miles away meant there wasn't enough time to pack up and evacuate. It's a simple matter of good scouting and fast marching. I confess that I don't know enough specifics about Scotland, but the Romans fought more than one victorious campaign through Scotland before Hadrian's Wall was built, and the "Picts" are not mentioned in literature until the next century. Hadrian's Wall and the Antonine Wall were certainly not invincible to heavy attack in the 4th century, but they pretty much eliminated any problem with small groups of raiders sneaking over the border.
Boudicca's revolt, by the way, there was no guerrilla activity, appart from harsh Roman reprisals that went on for months after the main British force was crushed. The Jewish Revolt is a better example, but even there, the Romans were pretty good about chasing down rebel raiders. In the Bar Kochba revolt of c. 132 AD, they even besieged rebels who had holed themselves up in cliffside caves. The Romans would lower archers in baskets to shoot in, or smoke the inhabitants out with burning brushwood, etc.
I'm not sure if we can determine exactly why the Romans ended up using the scutum/pilum/gladius combination. The origins go way back to the 6th or 7th century BC, when many Italian tribes were using such things. Troops with such equipment were used to back up the Greek-style hoplites of a Roman (or Etruscan) army up until the Republic was founded about 500 BC. After that, the hoplites went away and the scutum was used by all the heavy infantry. It does seem that the three lines of hastati, principes, and spear-armed triarii was effective against Gauls and similar opponents, but the system was being used against other Italians before the Gauls became a major problem.
Against mounted opponents, the Romans used their own cavalry, or allied cavalry. During the Empire, half of the army was formed of auxiliary units, and fully half of these were cavalry. And half of the auxiliary infantry units were actually mixed foot and horse. So well over a quarter of the Roman army was mounted, and very effective.
That's enough from me for the moment! If you want to know more about Roman stuff, a good place to visit is the Roman Army Talk board,
http://p200.ezboard.com/bromanarmytalk Or you can contact me directly, through my own website.
Enjoy, and Valete,
Matthew/Quintus, Legio XX
http://www.larp.com/legioxx/
