High Imperial Roman army vs Late Roman army

[Robert Vermaat]

I would vote for the roman army of the Principate because the roman armies of the late antiquity were only roman army in name.

I strongly disagree with that. The armies of the Principate were full of recruits from the provinces, and the auxilia was for 100% made up from non-citizens. The myth that Roman armies of Late Antiquity was full of barbarians has already been dispelled well and good.

[Robert Vermaat]

I would vote for the roman army of the Principate because the roman armies of the late antiquity were only roman army in name.

I strongly disagree with that. The armies of the Principate were full of recruits from the provinces, and the auxilia was for 100% made up from non-citizens. The myth that Roman armies of Late Antiquity were full of barbarians has already been dispelled well and good.

[Robert Vermaat]

So if an Principate army fought a Late Roman army on a field battle, who would win????

My vote would be for the Late Roman army. This army was more flexible (having to fight different enemies) and had a larger component of cavalry (again develeoped because the enemy had more cavalry). In that sense, the army of the Principate was good, but mainly fought lesser enemies. That would make a Late Roman army better equipped to win.

[Gesiþ]

And even if the Principate armies were "more Roman", that alone offers no advantage. If anything it would limit their options in battle compared to the Late Romans, who had a much more balanced and varied force.

[Flavivs Aetivs]

Although I'd have to argue that in close quarters, a Gladius and a rectangular Scutum would be much more effective than a Spatha, which was not exactly a thrusting weapon.

[AMELIANVS]

the roman armies of the late antiquity were only roman army in name.

I must also protest strongly against this.It's kind of old historical cliche who somehow managed to keeping still alive.
And even if later army was somewhat less Roman,as Gesith already said,this would not add automatically advantage to principate army.Most barbarians were considered formidable warriors by Romans themselves,also better physically equipped for warfare than average mediterranean man of very subtle body height,so basically they were as good as earlier soldiers were.What had changed,were the overall conditions and situation during which they had to serve.

[Robert Vermaat]

Although I'd have to argue that in close quarters, a Gladius and a rectangular Scutum would be much more effective than a Spatha, which was not exactly a thrusting weapon.

Beg to differ. A gladius is effective as a thrusting weapon, sure, but confronted with a solid wall of shields it's less effective.

[Antonius Insulae]

Magister Militum Flavius Aetius wrote:
Although I'd have to argue that in close quarters, a Gladius and a rectangular Scutum would be much more effective than a Spatha, which was not exactly a thrusting weapon.

Robert Vermaat wrote:
Beg to differ. A gladius is effective as a thrusting weapon, sure, but confronted with a solid wall of shields it's less effective.

That's why legionaries had pila, the javelins thrown against enemy lines was supposed to break their shield wall, pila will get stuck in the enemies shields, nailing some shields together, impaling some poor men through their shields and overall stuck into their shields, so they could't be pulled off of them, and the enemies had to abandon their shields. Then their bellies would be easy to pierce with gladii.

[Flavivs Aetivs]

But you could also argue that because the late romans had a larger supply of missile weapons, then both sides would have stuff stuck in their shields.

[Gesiþ]

And considering the larger numbers of enemies with similar weapons (angons, etc.) faced by the Late Romans, they might know how to deal with them more effectively.

[M. Demetrius]

A gladius is also a very effective weapon for drawing cuts (line on knee tendons) and slashing (like exposed limbs and necks). The belly thrust would most often cut into intestines, leading to fatal peritonitis, but that death is not immediate--regardless of what they show us on television. Exsanguination, on the other hand, if a thrust cut one of the large abdominal/thoracic arteries, would be just a matter of a half minute or so before the stabbed one lost consciousness due to shock and reduced blood pressure.

Late Roman spathae were not really intended to be used in the same way as a gladius, however, so it's not an easy comparison. The spatha more closely resembled a Gaulish sword, but it's clear enough that the Gauls were defeated by Republic armies, then Imperial armies. Spears were the main weapon of both late Romans and Gauls/Germanics/"Celts".

All these armies, from Republic to "barbarian" to Late Roman utilized light infantry whose primary initial weapon would have been javelins, slingers and archers. (Sorry, no TRW head hurlers) Late Romans had all these things plus the plumbata, a notably dangerous weapon.

[Timianus]

Too many variables here. If you assume both have equal numbers, are adequately supplied, motivated (i.e. being paid), engaging in a set-piece battle on open ground with no natural barriers to protect the flanks of either army, then I would estimate that the late army would have a slight advantage over the principate army. My reasoning is as follows:

1. Overall, i think the LRA had better tactical leaders, as officers tended to be from the equestrian class and battle-tested, versus some son of a senator doing his tour of duty.
2. Once the principate army exhausted their 2 pila, they would do a full frontal assault. The late army would counter with missiles and plumbatae while being charged, taking out some of the first ranks.
3. Once the lines met and engaged, the late army would have a distinct reach advantage from their spears and ability to form a "wall" with spears protruding.
4. The late army would also have a cavalry advantage and would likely rout the light principate cavalry.
5. The late army would be more adept at flanking manoeuvres, due to their lighter armour and shields.
6. The late army would also likely have a more heavy artillery weapons.

On the other hand, I do think that the principate army would be slightly better disciplined and better able to exploit any breaches in the line or, conversely, hold the line.

Whoever was victorious, it would be a meat-grinder of a battle, unless the late army was able to outflank early on.

[Timianus]

Which brings up an interesting question...how many of the tactical and equipment changes were due to fighting foreign enemies vs civil wars.

[C Crastinus]

3. Once the lines met and engaged, the late army would have a distinct reach advantage from their spears and ability to form a "wall" with spears protruding.

I'm a little skeptical about that. Many spear thrusts would have glanced off the rounded scutum rather than penetrating it when they charged into close quarters, and once they had closed in, wouldn't the shorter thrusting gladius have had an advantage over the longer spatha? Similarly, didn't the Spartans prefer their shorter swords because they were more effective when fighting up close? Instead of a reach advantage, wouldn't it have been a reach disadvantage once the legionary had gotten past the spear point? I know the legions couldn't do much against the Macedonian phalanx, head on at least, but that was a different creature altogether. Caesar's legions didn't seem to have much trouble with the shield walls of the Gauls.

Wouldn't the gladius' lighter weight have been an advantage in a longer fight as well, since the man wielding it wouldn't tire as fast as the man wielding the heavier spatha?

Weren't the auxiliaries during the Principate armed quite similar to the Late Roman army, with spears and the round flat shield? During the civil wars, that of AD 69 for example, there must have been instances of legionaries fighting auxiliaries so armed. If the spear and shield wall proved more effective in those engagements, would the Romans have continued to arm their auxiliary units in a manner superior to their legionaries?

I haven't come across any reasons in the ancient sources as to why the auxiliaries were armed with the flat round shield and spear instead of with the same equipment as the legionaries. Was it perhaps because the auxiliaries were frequently deployed on the flanks? Since the flanks were more likely to be engaged by cavalry, were the auxiliaries perhaps armed that way so that they could better withstand cavalry attacks?

Was the change in equipment in the later period due to the fact that they were facing cavalry more often, rather than because it was superior to the earlier armament in an infantry vs. infantry scenario?

[Flavivs Aetivs]

Auxilliaries didn't have a ton of missile weapons like the Late Romans did. Plumbatae and Lancaea/Veruta would have rendered a large portion of a principate shields useless.