A bit of a fantastic scenario, but as arms and armor play such a fundamental role in such a fantasy confrontation, I thought I'd throw it out for thoughts:

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The year is 106 C.E. At the head of an astonishing thirteen legions, Emperor Trajan of the Romans leads one of the largest invasion forces the world has even seen against the kingdom of Dacia. Four years before, Trajan had successfully brought the rebellious King Decebalus to heel through military action, forcing him to become a client king of the Empire. Refusing to be cowed by the might of the Imperial legions, the upstart monarch reestablished his power base and destroyed the Roman garrison in his country. Exasperated, Trajan makes the fateful decision to completely destroy Decebalus’ power base and annex the territory for Rome.

At the head of a small contingent of his grand army, Trajan marches through Gaul toward the east and Dacia when he is given a most perplexing report by one of his scouting parties. To his utter surprise, the Emperor is informed that an unknown, foreign army has been spotted marching from the north directly through of Gaul. Ordering his scouts to acquire more information about the nature of this mysterious force, Trajan wheels his own army northward with the plan of intercepting these invaders.

Trajan surveys the forces at his disposal. While it had been recently created, Legio XXX Ulpia Victrix was a collection of some of the best veterans legionaries the Empire had to offer, provinding 5,300 heavy infantry for the Emperor to work with. Each legionary is armored in lorica segmentata, and armed with a gladius and two pila. To support this force were two main auxilary contingents. Firstly, a full ala miliaria made up of just over 1,000 veteran Gallic cavalry known as Conttarii, who are more heavily armed and armored than their predecessors, possessing chain mail armor, the longer spatha, and heavy lances. Secondly, two cohorts of Syrian archers which total about 1,000 men also accompany and support the legion. Well known throughout the Roman world, these Syrian archers are armed with their vaunted composite bows, though they can be called upon as light skirmishers as well. To finish the force, Legio XXX also had a standard array of artillery, one Carro-Ballistae per century for a total of sixty (also ten Onagers per legion, but these were generally only utilized for sieges, unlike the ballistae, which were designed largely as field artillery).

Troop Total: 7,300 (+60 ballistae)

Meanwhile . . .

The year is 1415 C.E. For decades, a state of total war has existed between France and England, with intermittent campaigning always taking place on French soil. Though the beginning of the war saw both Edward III and his son the Black Prince leading English forces to spectacular victories over the French chivalry arrayed against them, the latter decades of the conflict have seen English power waning. Coming to the throne only two years before, Henry V resolves to reverse this trend and capture by force what he sees as his birthright; both the Duchy of Normandy as well as the French throne.

Landing in northern France, Henry and his invasion force successfully besieges Harfleur before he decides to move his force to Calais where he can winter his troops. As he begins this march however, his forward scouts provide him with word that a mysterious force very unlike any normal French army is moving north at incredible speed to cut off his flight to Calais. Further, it is noted that enemy scouts have been spotted surveying the English force. Ordering his own scouts to do likewise, the King continues his march toward Calais in the hopes of reaching it before this mysterious force catches up to him.

Henry surveys the forces at his disposal. Having left a portion of his army behind to defend Harfleur, Henry currently possesses 1,500 men-at-arms, made up of English knights and their various retainers. Up to half of these can be called upon to serve as knightly heavy cavalry, the remainder serving in a strictly heavy infantry capacity. The grand majority of these men, both the mounted and dismounted variety, are armored in chain mail, with a variety of weapons from longswords to axes to maces, as well as heavy lances if serving as cavalry. A small portion of these men, 150 of the richest knights and lords, have plate mail armor. The remainder of Henry’s force, some 5,500 men, is made up of the archers, who have proved their incredible effectiveness throughout the war. These marksmen, coming from much more humble origins, are protected by lighter leather vests. They wield the infamous longbow, though they can also be called upon to act in a skirmishing role.

Troop Total: 7,000

Underestimating the incredible marching speed of the mysterious army, Henry finds his forces cut off from Calais, instead facing an enemy force just over two kilometers away. The terrain is open plain, flat and grassy, with no hills around. Disconcerted at being so easily out-marched, Henry takes some solace in the fact his scouts report no signs of knightly heavy cavalry as the French could bring to the field from the enemy force, though the incredible discipline of the army at march is noted. His scouts are able to give him a basic idea of the enemy force arrayed against him, leaving Henry perplexed as to what ally the French could have called upon to aid them in the war. Considering his options, he prepares his force for the seemingly imminent battle.

Meanwhile, sitting on horseback surrounded by his elite Praetorian Guard, Trajan looks upon the army arrayed against him with similar surprise while the Roman war machine moves quickly and efficiently into battle formation. While certainly not matching the unrivaled discipline of the legions in his eyes, the mysterious force that moves into battle order against the Romans is certainly more organized than the majority of enemies he has seen and fought against, with the possible exception of the eastern kingdoms such as the Parthians. Prior to deployment, his scouts give him information about the enemy, including their large array of archers, as well as the very heavy cavalry they possess.

I’ve kept the tactics open to allow suggestions on how each side would deploy with at least a limited knowledge of enemy forces. Keep in mind that this is an open plain, with plenty of room to maneuver for both sides, allowing for potential flanking or any other tactics for either side. I’ve outlined the forces as true to their respective time frames as possible, providing specifics to promote debate on specific tactics utilized, rather than what the make up of such forces would be. The English force as mentioned is the very same that landed to eventually fight at Agincourt, though I’ve increased their commonly accepted numbers somewhat. With the Romans, I’ve provided simply one example of the wide assortment of arrays used in pitched battle.

Thoughts on possible outcomes?

You really put a lot of though into this, didn't you?

Well, it might have been a more complex question given some other Medieval army. Perhaps one with more pikemen and fewer archers. As it stands, I predict that the English will array their forces much the way they did at Agincourt, given the success of similar tactics at Crecy and Poitiers. Then, I'm going to go out on a limb and put my money on our Hal's archers making embarassingly short work of the Romans. The English bows probably have greater range than anything the Romans have ever seen before. The Romans will probably defend themselves admirably with all of their fancy shield tricks, but I don't think it would save them under those circumstances. With 15,000 or so arrows per minute falling on the Romans while they walk (not ride) towards the English lines, I'm not sure that even the mighty testudo could save them, though they'll probably last quite a bit longer than the French did.

I don't know though, perhaps I'm not giving the Romans enough credit. It's late and I'm tired. I'll think about it at work tomorrow and see if some sleep will change my opinion. I have to add, though, that I really hate these katana vs. rapier kind of questions. I tend to think that tactics and weapons can only be accurately judged in the context of their own time and place. We can only mix and match so much before it starts being silly and then we lose any chance of learning what it was we wanted to learn in the first place.

Well do not forget about auxiliary horse archers.Properly used they can cause some damage in the lines of English archers while they try to brake tetsudo formations.I think it is all in tactics used-not in the arms and armour-they are better in english forces but less comon...I believe not all of English infantry are using heavy armour.And all the Romans use lorica segmentata....

Here's my random thoughts

15,000 arrows per minute is pretty impressive, but how for long? Arrows don't last for long, and unless you have carts full, the testudos only have to weather a few volleys. 5000 archers x 20 arrows each = 100000 arrows / 15000 APM = 6.6 minutes of devastating arrow fire. And twenty arrows is a lot to march with. How many arrows did a medieval archer carry, or were the arrows passed out from a baggage cart?

Lorica Segmentata would deflect arrows a lot better than Lorica Hamata, and a rounded scutum might deflect more arrows than you think, even bodkins. The Romans don't have to worry about their unbarded horses being cut out from under them, cause they aren't on horseback, and they are generally more protected than the French footmen, so long as the testudos hold. My knowledge on Classical history if a bit fuzzy, but would these Romans have faced the Sarmations yet? If so, they should have some knowledge in dealing heavy cavalry, so 150 knights might not be a coup-de-gras. Not that I'd want to be on the business end of any lance. If this is a grassy (not muddy) field then we can expect the Henry's heavy cav to be in peak form, and most effective.

Another aspect might be the relative ineffectiveness of a gladius against mounted troops. Sure you can stab his horse, but unless he falls and breaks a leg, he's still a major threat.

Good topic. :D

Also if the Romans are not attacked right away they might make camp which for the Romans the S.O.P. would be to entrench. This is something the Romans usually did every day at the end of march.

The Carro- Ballistae might be able to equal the range of the archers and would be a serious threat to even plate armour.

The onagers might be useful in breaking up an infantry attack ???

Not sure if many Romans would have carried slings ? But slings with lead shot can outrange archery.
Now there might be a small number of specialists slingers but I would think that most Roman legionnaires would have some
minimal competence with a sling and if I were equipping a legionnaire, a sling would not be much of an extra burden.

As someone else said, tactics would be more critical to the outcome than the specifics of the weapons.

Roman discipline would be a definite plus.

In close combat the well armoured Knights would be hard to deal with until they were exhausted: The Romans could keep pressure against the Knights by rotating fresh legionnaires against the small numbers of Knights and try to turn it into a pushing match.

On one hand you have Romans hunting Dacians.

One the other, English more or less hunting French.

Both sides can clearly tell that the force they have encountered is not the one they are looking for.

I'm thinking they pitch camp and work out a mutually beneficial alliance. Assuming egos do not get in the way of negotiations both sides have more to gain by fighting together than they do by fighting each other, because both haveother enemies to deal with.

I came up with a similar scenario at work today. Both sides see that strange things are afoot at the Circle K and they each send hearalds under a flag of truce to talk. Each side is naturally shocked as soon as the other opens his mouth. Eventually, Harry's priests overcome the language barrier that exists between Classical Latin and Medieval Latin (unless Mel Gibson is there filming, in which case the Romans would already be speaking Medieval Latin :confused: ). Over much wine, they'll unravel the metaphysical mysteries that surround the concept of time travel, scout the surrounding area to establish just who popped into who's century and make some kind of alliance for the benefit of both parties. After all, they're all civilized men. All of this is assuming that Harry's priests don't decide that the Romans need to be converted or something silly like that. That could ruin everything. If we're in 1415, the Romans eventually return to Italy, which is so weak and divided that they conquer the entire country and establish the Second Roman Empire. Machiavelli acends the throne some seventy or eighty years later. Much fun is had by all. :p

Sorry. It's been that kind of day.

Well we seem to have the outline of a good alternate history Sci. Fi. story: One of my favourite genres and good excuse for all sorts of anachronistic arms and armour " living history sacrilege " :p :p :p Sorry, couldn't resist :D in the right context the historically accurate mindset is the right one, but it doesn't mean we can' t have fun with crazy alternatives.

The idea that they might negotiate rather than fight for no good reason makes a lot of sense to me, but the purely tactical original question could still be examined further. ( In the spirit of the original intent of this topic. )

I think this sort of topic is valid if one considers tactics in themselves are a form of arms & armour study as a type of martial art in the widest possible sense of the word: The fact that it is not " serious " history doesn't mean that it has no value. It seems to me a way to explore the various " paths not taken " a way of speculating how different fighting systems would have affected each other if they had been put in competition with each other.

Hey, here's a serious question. Henry V took Harfleur with twelve siege guns. Does anyone know if he took those North with him, or did he leave them there?

I think this whole question is quite silly. Fun, certainly, but silly. Being a medievalist, I'm going to inevitably make the English win. So, rather than attempt to hide my bias, I'm just going to list the advantages of the English:

Stakes. These effectively render the Gallic cavalry useless, as they did with the French cavalry in the battle of Agincourt (According to Desmond Seward). They also slow and stagger the advance of the Legionaries, which provides for a great amount of arrow-related casualties, especially with those big ol' shields.

Range: The longbow effectively shoots a good 180 metres. The composite bow may have a similar range, I don't quite know, but what I gather from this thread: http://www.myArmoury.com/talk/viewtopic.php?t=5824&start=40 it may actually exceed that range, though 1000 archers on horses can quickly be cut down by less-than-discriminate firing from 5,500 bows, I would think.

Maneuverability. Assuming the Romans get tired of getting pelted with arrows and choose to advance, they're liable to be surrounded by the more lightly-armoured and less tightly-packed longbowmen. This might be key to winning the battle, but I don't know.

Artillery: I can see a small contingent of English knights moving out to take care of the ballistae, then swinging around to confront the Legionaries in the rear, possibly causing a good deal of routing..

That's my extremely biased opinion.

Oh, and Gavin, each English archer carried 50 arrows (Seward again)

Unfortunately, they didn't have any guns with them.

A few wild theories on the effectiveness of English archers....

The 15000 arrow per minute figure is consistent with average estimates I have run accross, and actually lower than some occasional higher claims I have read for the English archer contingent capability. Also their bags were replenished with new arrow bags during the heavy volleys. In terms of total quantity of arrows (credible in terms of surviving records of inventories) they had access to armories stocked with sufficient quantities to do this for something on the order of 15 minutes (between 225,0000 arrows to 500,000 arrows were available in serveral major engagements.) Arrow inventory was actually a pretty big portion of what was tracked and reported, outweighing records of armour and virtually any other type of logistical supply significantly. Another way of looking at this is that there may have been roughly 30 to 60 English arrows available on average for each opponent in most actual battles as well as the hypothetical case considered here. However, full capacity volleys were generally concentrated upon advancing infantry or cavalry depending on the situtation, and the arrow count per man targeted in serious could be debated to be higher (perhaps more than 100 arrows per advancing opponent if multiple charge attempts are made, as was typically the case in actual history, feints and retreats by both sides with English volleys at appropriate range each time....)

I can't get any consistent estimate of what a typical broadhead weighed (anywhere from 2 oz to 8 oz.) In fact archeological sites have yielded varieties of arrow types and weights (bodkin, and various types of broadheads) that were used at the same engagement. Fired at long distance these lighter ones do not seem capable of mortal wounds. The typical "quantity theory" advocates that adequate chances existed for bleeding due to wounds, blinding opponents through hits in eye slits, and disrupting cavalry charges (unnerving less than heroic mounts or riders) to the extent that the charges are scattered and poorly coordinated by the time they reach the English lines. I think there is a very high demoralization factor involved, even if the arrows did not do as much physical wound damage at long range as some believe.