Got a Real-World Weapon, Armor or Tactics Question? Mk. XXIV

[Galloglaich]

Very interesting video I found while browsing Youtube.

I'm not sure exactly how accurate it is, but it's from a Spanish movie and shows the clash of two pike units in the 30 Years War. Before the infantry melee, the unit gets pummeled by artillery and stands off a cavalry assault.

What I though was kinda nifty was how when the ranks of pike meet, they don't smash into one another, but kind of fence a bit at distance. Then a few men with short weapons dash in under the pikes and start slashing and stabbing.

https://www.youtube.com/watch?v=4y6agtVxWi8&t=623s

Again, I don't know how much of this is accurate and how much is show biz, but it's worth a watch.

If anybody can critique it for accuracy, that would be nice as well.

Yeah that movie Alatriste is pretty famous in HEMA circles, there are some good rapier duels in there too and other realistic stuff like French peasants getting 'transported' in cages to the New World.

It's one of a handful of movies in the last 60-70 years which are anywhere near the ballpark of reality for this type of era. The best others are either Polish (the With Fire and Sword films), Japanese (basically all the Kirosawa historical dramas) and a few of the early Anglo American films when they were still training actors to fence.

The Deulist is pretty good as is Rob Roy for more recent films.

This 1940 version of the Mask of Zorro has a really nice duel

https://www.youtube.com/watch?v=nB8tiSMCwRE

edit- fixing youtube link I forgot this forum doesn't have the youtube embed thing

G

[Mike_G]

Yeah that movie Alatriste is pretty famous in HEMA circles, there are some good rapier duels in there too and other realistic stuff like French peasants getting 'transported' in cages to the New World.

It's one of a handful of movies in the last 60-70 years which are anywhere near the ballpark of reality for this type of era. The best others are either Polish (the With Fire and Sword films), Japanese (basically all the Kirosawa historical dramas) and a few of the early Anglo American films when they were still training actors to fence.

The Deulist is pretty good as is Rob Roy for more recent films.

This 1940 version of the Mask of Zorro has a really nice duel

[youtube]nB8tiSMCwRE[/youtube]

G

Thanks for the info.

I've seen The Duelists which I loved, and Rob Roy, since I am of good Franco-Irish Jacobite stock and married a Scot. I've seen a lot of old Hollywood fencing movies, which are fun, but it's largely Olympic style fencing, which was my thing, but I don't know how realistic it is. The 1974 Three Musketeers with Oliver Reed and Michael York had what looks like pretty good fencing in it.

In other news, I found a new HEMA group near me and was going to ask if you known them. Tried to PM you but the formus says your massages are full.

[Galloglaich]

Thanks for the info.

I've seen The Duelists which I loved, and Rob Roy, since I am of good Franco-Irish Jacobite stock and married a Scot. I've seen a lot of old Hollywood fencing movies, which are fun, but it's largely Olympic style fencing, which was my thing, but I don't know how realistic it is. The 1974 Three Musketeers with Oliver Reed and Michael York had what looks like pretty good fencing in it.

In other news, I found a new HEMA group near me and was going to ask if you known them. Tried to PM you but the formus says your massages are full.

Sorry about that will clear messages

[Raunchel]

Here I am again, with a whole bunch of questions. This time, they actually mostly deal with arms, armour, and combat, so I think that I’m improving. :)

1) Does anyone happen to know how fast a trained soldier in mail and bearing weapons can charge? I’m mostly looking for a rough figure, because I guess that there would be a lot of individual variation. And how would this speed be affected by being in a forest (moderately well-kept, so not too extreme undergrowth)?

2) I have recently also become interested in slings and their application in warfare. Right now, my understanding is that a good hit with a stone will break bones and the like when hitting unarmoured parts of the body, but that armour with padding under it will not do much more than cause some bruises. Would I be correct in assuming this? (they would be using stones, not lead bullets) And does anyone know how fast a slinger could be shooting?

3) If someone would be loading a crossbow with a cranequin, and let go of the cranequin halfway through the loading process for some reason, would the string remain in place or would it snap back to its normal position?

4) Continuing on the topic of crossbows, would one normally keep the crossbow fully loaded, so to say, whenever one ventures anywhere dangerous (for a few hours or so), or would it only really be loaded when necessary?

5) What kind of sound would a crossbow bolt or arrow flying very closely past someone make?

[Clistenes]

A question:

I have read several times in this thread that curved swords like sabres and scimitars are better at defense than longswords, arming swords and similar straight blades... but, is that true always, or only when people use curved swords to duel each other? has it been put to test when somebody uses a curved sword against an straight-bladed weapon?

I have no fencing experience at all, but it sound weird that a slashing weapon with the center of gravity closer to the point would parry faster than another weapon or similar length with the center of gravity closer to the pommel...

Could you explain to me what exactly makes curved swords better at defense?

[Knaight]

I have recently also become interested in slings and their application in warfare. Right now, my understanding is that a good hit with a stone will break bones and the like when hitting unarmoured parts of the body, but that armour with padding under it will not do much more than cause some bruises. Would I be correct in assuming this? (they would be using stones, not lead bullets) And does anyone know how fast a slinger could be shooting?

A stone can easily kill an unarmored person, and it doesn't just break bones - it can punch through skin and muscle no problem. Armor helps, but it doesn't reduce slings to just inflicting minor bruises (particularly if heavy stones are used).

[Brother Oni]

Here I am again, with a whole bunch of questions. This time, they actually mostly deal with arms, armour, and combat, so I think that I’m improving. :)

1) Does anyone happen to know how fast a trained soldier in mail and bearing weapons can charge? I’m mostly looking for a rough figure, because I guess that there would be a lot of individual variation. And how would this speed be affected by being in a forest (moderately well-kept, so not too extreme undergrowth)?

2) I have recently also become interested in slings and their application in warfare. Right now, my understanding is that a good hit with a stone will break bones and the like when hitting unarmoured parts of the body, but that armour with padding under it will not do much more than cause some bruises. Would I be correct in assuming this? (they would be using stones, not lead bullets) And does anyone know how fast a slinger could be shooting?

3) If someone would be loading a crossbow with a cranequin, and let go of the cranequin halfway through the loading process for some reason, would the string remain in place or would it snap back to its normal position?

4) Continuing on the topic of crossbows, would one normally keep the crossbow fully loaded, so to say, whenever one ventures anywhere dangerous (for a few hours or so), or would it only really be loaded when necessary?

5) What kind of sound would a crossbow bolt or arrow flying very closely past someone make?

1) Over short distances, about as fast as a normal person can sprint, so I'd say ~7.5 m/s (they'd cover 100m in ~13 seconds, which is a fair pace). Mail would affect endurance (not an issue at charging distances) and turning speed (they're not stopping or turning on a dime), which again isn't an issue if you're going to smash into an enemy combatant at the other end. In a forest, I'd say the speed would be halved if crashing through undergrowth, or virtually unaffected if following a path or in something like a pine forest.

2) I'm not very well versed in slings I'm afraid, but I've read that slingers could do some decent damage to armoured opponents.

3) Cranequins have a ratchet mechanism which prevent it from slipping, so you can stop any time you like. However you would be very ill advised to attempt to take the cranequin off if the string is under tension and not held by the nut (either complete the spanning or let it down back to its brace height).
Here's a video of a cranequin in action: link.

4) One of the main advantages of a crossbow over a bow is that it can be held under full tension and only loaded and shot when required. One common trick was to secure the bolt to the flight groove with a drop of hot wax, so it was ready when you needed it when out looking for trouble.

5) Assuming you're not including the bow noise or the sound of wood on wood from the arrow against the bow, it's surprisingly quiet: here's some aluminium (I think) arrows being shot from a suppressed (modern) recurve. Here's the sound of a longbow with wooden arrows being shot from the archer's end. It's more of a quiet whisper than the 'whistling' it's more typically described as (if your arrow's whistling in flight, then it's either a special noise maker arrow, or you have crappy arrows with poor flight characteristics).
The stereotypical 'boing' sound is the arrow connecting with the target and causing vibration - this won't happen in your example.
In the event that an arrow does connect, it depends on what it's hitting - wood tends to go 'thunk'; straw tends to be rather quiet; metal armour has a very quick metal on metal rasp (from the arrow head) and flesh generally has a wet 'smack', which may be followed by sounds of pain.

[warty goblin]

1) Over short distances, about as fast as a normal person can sprint, so I'd say ~7.5 m/s (they'd cover 100m in ~13 seconds, which is a fair pace). Mail would affect endurance (not an issue at charging distances) and turning speed (they're not stopping or turning on a dime), which again isn't an issue if you're going to smash into an enemy combatant at the other end. In a forest, I'd say the speed would be halved if crashing through undergrowth, or virtually unaffected if following a path or in something like a pine forest.

Having done some woods walking in mail, it can sometimes actually speed a person up. Mail is entirely* bramble-proof, which can be a real asset in dense enough brush. Of course nobody's charging anywhere in that sort of undergrowth anyway.

*Except for thorns that get broken off between links, and work their way inwards. Fun times.

[Brother Oni]

Having done some woods walking in mail, it can sometimes actually speed a person up. Mail is entirely* bramble-proof, which can be a real asset in dense enough brush. Of course nobody's charging anywhere in that sort of undergrowth anyway.[/SIZE]

I was thinking more about trip hazards, but I'll defer to your experience.

[KarlMarx]

2) I have recently also become interested in slings and their application in warfare. Right now, my understanding is that a good hit with a stone will break bones and the like when hitting unarmoured parts of the body, but that armour with padding under it will not do much more than cause some bruises. Would I be correct in assuming this? (they would be using stones, not lead bullets) And does anyone know how fast a slinger could be shooting?

Slings are negated by some armors and not by others, as far as I can tell. At short range with little padding, a lot of their force will carry over, likely resulting in bruises. Over longer ranges, they lose power. This is doubly true of stones, which have less mass for the same volume than lead bullets and thus less momentum and more air resistance. A single hit probably wouldn't do much to individual soldiers heavily armored, but lightly equipped slingers could rain down shot over time and wear down their targets.

As to the reload question, many sources indicate that they in fact had a quite rapid reload speed. Balearic slingers in the Roman army were known for their speed and accuracy, and in other cases trained soldiers could easily become quite proficient with the loading process. Ultimately, I'd guess that aiming and throwing the projectile would probably take a slight majority of your time, rather than reloading.

Furthermore, the real advantage of the sling is that it's so light, cheap, and convenient. Heavy infantry can easily carry one to give them some ranged capacity, while light infantry can use them to harass the enemy with great efficacy. Indeed, at Hastings the Norman infantry were equipped with slings and used them in their assault.

So in the long run slingers will probably not be as purely powerful as archers with the equivalent level of training, especially by the Medieval period when heavier draw weights entered the battlefield (part of what made the Balearics shine so much was the fact that archers didn't have that powerful bows at the time, and thus the effective range of a sling could actually be higher than that of a bow). However, they are a lot easier to train and a lot cheaper to employ, so they definitely have their uses on the battlefield.

[DerKommissar]

One of the most severe punishments in medieval law was exile. Greatly feared. Town law wasn't that strict but if you disgraced or dishonored yourself it could start a downward spiral. Once exiled from the town (which could either be temporary, 1 year and 1 day, or permanent - 100 years and 1 day) you had a chance to get into another town but it would get harder if your reputation suffered. If you were known to have done something really bad you may be marked like with a cut on your ear or something.

G

A bit late to the party but just two examples:

In modern german you can call someone a "schlitzohr", refering to him as "having his ear cut" meaning he is a petty criminal or a naughty child.

In bavarian/austrian you can call somebody "gschert" (= shorn) if you think he is somebody without manners. I heard two explanations: 1) you could avoid punishment by becoming a brother in a monastry where you got the tonsure. 2) in some medival law peasants where not allowed to wear long hair, but citizens were, so to sheer off the hair could symbol a loss in status.

---


About trade/crafts restrictions: the protection of local crafts and trades by cities didn't end with the city walls, but there were also areas around it called Bannmeile (german) or banlieue (french) where you were only allowed to buy products by "licensed" vendors.

---

About the "stadtluft macht frei": this was sometimes working in a similar way for bigger realms, so that it could happen, that a guy from genoa brings a slave with him to germany, loosing him in the process as slavery was abolished there.

Just some things i wanted to note while catching up with the thread :)

[Kiero]

So in the long run slingers will probably not be as purely powerful as archers with the equivalent level of training, especially by the Medieval period when heavier draw weights entered the battlefield (part of what made the Balearics shine so much was the fact that archers didn't have that powerful bows at the time, and thus the effective range of a sling could actually be higher than that of a bow). However, they are a lot easier to train and a lot cheaper to employ, so they definitely have their uses on the battlefield.

Just on this point, bows in the western Mediterranean in antiquity were predominantly self bows and not very powerful. Slings (with lead bullets) were a superior weapon.

However, in the eastern Mediterranean, they had access to Persian and steppe bows, which were composite and much more powerful.

[Knaight]

Just on this point, bows in the western Mediterranean in antiquity were predominantly self bows and not very powerful. Slings (with lead bullets) were a superior weapon.

However, in the eastern Mediterranean, they had access to Persian and steppe bows, which were composite and much more powerful.

There's also the matter of how range affects power. An arrow shot in a high arc and just falling is nowhere near as dangerous as an arrow recently shot out of a bow. Lead glandes* falling from a height after slinging in a high arc were still really dangerous due to their high densities, losing relatively little energy to air resistance and hitting hard enough to go into the target if it hits somewhere reasonably soft and to at least partially penetrate while breaking bones if it hits somewhere hard. Armor helps here (and shields help a great deal), but the idea of total immunity is hogwash.

*And to some extent even the clay ones that were essentially carefully shaped rocks and were thus largely less dangerous than lead.

[Vinyadan]

Something I found interesting: in 2.24, Polybius gives a calculation of the men able to bear arms on the Roman side at the start of the war against Hannibal, which totals at 700,000 (!) footmen and 70,000 horsemen. About 261,000 of both kinds were in arms when Italy was invaded.

He also gives some info about levy numbers for the single Roman federates, which must be interesting for ancient demography.

[Kiero]

Something I found interesting: in 2.24, Polybius gives a calculation of the men able to bear arms on the Roman side at the start of the war against Hannibal, which totals at 700,000 (!) footmen and 70,000 horsemen. About 261,000 of both kinds were in arms when Italy was invaded.

He also gives some info about levy numbers for the single Roman federates, which must be interesting for ancient demography.

Not really surprising given there were 2-3 million people in Italy at the time, and their militia system meant every free male above a certain level of property and between the ages of 16 and 60 had to spend some summers in the Legions. And all of them could be called up in dire emergencies.

[KarlMarx]

Though it should be remembered that many of those cities were uncertain at best when it came to helping the Romans.

[Roxxy]

This is really more of an opinion thing than a factual one, but, during either World War, would you say the capabilities of the infantry carried flamethrower were ever worth the costs and limitations, taking into account the differing circumstances on differing fronts?

[rs2excelsior]

This is really more of an opinion thing than a factual one, but, during either World War, would you say the capabilities of the infantry carried flamethrower were ever worth the costs and limitations, taking into account the differing circumstances on differing fronts?

Flamethrowers are very useful for assaulting fortified positions, specifically bunkers. The firing slits in bunkers are usually pretty small targets, but a flamethrower can generally get its burst of flame inside, which will basically neutralize the bunker. Also, flamethrowers were used in the Pacific in WWII to clear Japanese underground tunnel networks--the flame could be used to consume the oxygen in the tunnels, suffocating the defenders inside. Given the extensiveness of bunkers and (in the Pacific) underground fortifications, I'd say they were generally worthwhile. Plus the psychological effect could be prodigious--though that could draw more fire to the soldier operating the flamethrower. That said, there were other ways to assault these positions--all rather dangerous--and I'm not sure I'm qualified to say whether the flamethrower was better or worse.

Basically all the major combatants in WWII used them through--and at least in the US Army, after--WWII, which I think does speak to a degree of their effectiveness.

[Kiero]

Though it should be remembered that many of those cities were uncertain at best when it came to helping the Romans.

True, but it doesn't change the main point that numbers as high as those aren't outlandish for the deep reserves of manpower the Romans could draw upon.

[KarlMarx]

Yes, but going from the upper estimate of 3m people and a relatively low median age, say 15, which would be accurate for a low-life-expectancy, high childbirth rate society like that of the Romans, a back-of-the-envelope guesstimate would suggest that the military manpower for the period of Italy as a whole (all men of age greater than 15), was only about .75 million, if not less, depending on the adult sex ratio. Given again that the Romans couldn't depend on many of their allies for support, it would appear that Polybius' numbers were a little high (perfectly believable, given the tendency of ancient authors to exaggerate). If 2/3 of cities over the course of the war supported the Romans, they would be looking at a maximum manpower pool of 500,000 by this math, and again probably less. Remember, though, that this math is highly hypothetical, back-of-the-envelope material.

[Martin Greywolf]

This is really more of an opinion thing than a factual one, but, during either World War, would you say the capabilities of the infantry carried flamethrower were ever worth the costs and limitations, taking into account the differing circumstances on differing fronts?

Fun fact: US considered using these again in urban combat in Afghanistan and Iraq, but the idea went nowhere - not because flamethrowers themselves were deemed not effective, but because there was no manufacturer ready to make them, not without a big initial investment (basically building a new factory for them from the ground up). It was mentioned in Forgotten Weapons YT channel interview with a Vietnam war era flamethrower expert.

I have read several times in this thread that curved swords like sabres and scimitars are better at defense than longswords, arming swords and similar straight blades... but, is that true always, or only when people use curved swords to duel each other? has it been put to test when somebody uses a curved sword against an straight-bladed weapon?

I have no fencing experience at all, but it sound weird that a slashing weapon with the center of gravity closer to the point would parry faster than another weapon or similar length with the center of gravity closer to the pommel...

Could you explain to me what exactly makes curved swords better at defense?

Uh, no they aren't.

First off, curved swords - let's use the term sabres - aren't necessarily slashing weapons with PoB further from the hilt, it depends on the specific type of the sword, and often on specific sword, taking early Magyar sabres as examples, you have many choppy types and equally as many pointy stabby types, both with slightly curved blades, and they look virtually identical (stabby ones tend to have arming-sword shaped tip, but not always). The same goes for arming swords incidentally, there are some that feel really good in the hand, made for fencing, and others that have PoB far from the hilt, making them cleavers with comparatively little agility.

Then there's the problem of what curved really means, most sabres have vary slight curve on them, allowing you to stab with them reasonably well, extreme curves that turn a normal stab into a push slice are comparatively rare.

There's only one reason why you'd hear a claim like this I can think of, and it's a rather unfair comparision of high medieval arming sword with a basket-hilted sabre - in this case, the sabre is clearly better at defense since it has the basket hilt, but then you're not really comparing like with like. Compare a 13th century sabre with a 13th century sword, and you'll find out that they can be practically identical.

What sabres are better at are slicing cuts, because of a number of reasons, they tolerate you messing up the blade alignment a little better.

[gkathellar]

Adding to the above, it's been noted now and again that saber duels can go on for a long time, but this doesn't necessarily mean they're better for defense - just that saber-on-saber is characterized by effective defense. And you certainly can't generalize that to all curved swords.

[Mike_G]

Saber drill in the 18th-19th century emphasized a lot of defense, probably because it was expected to be used without a shield or much armor. I don't know how the curve would make it better for defending.

The curve does let you make some sneaky point attacks that are harder to parry.

[Roxxy]

Does anyone know to what degree nose art and the like has been tolerated among American aviation throughout history? I know plenty of examples exist, especially from World War 2, but existing doesn't mean being allowed, and I don't see it being tolerated in today's armed forces. Was it ever allowed? If so, when was it banned? If it was never allowed, how commonly was that rule broken, and when did it become universally enforced?

[fusilier]

Does anyone know to what degree nose art and the like has been tolerated among American aviation throughout history? I know plenty of examples exist, especially from World War 2, but existing doesn't mean being allowed, and I don't see it being tolerated in today's armed forces. Was it ever allowed? If so, when was it banned? If it was never allowed, how commonly was that rule broken, and when did it become universally enforced?

During WW1, customization of the paint ranged from a symbol or slogan on the fuselage (sometimes the wings), to a completely custom paint job over the whole aircraft. The more complete repaints were more common among German pilots, but did occur occasionally among the Allies and other Central Powers.

As for Americans in WW1, it appears to have been rare, but I have seen some really colorful SPAD fighters in American colors. Although they may have been painted that way after the Armistice. See here:
http://www.cbrnp.com/profiles/quarter1/showbirds.htm

[Brother Oni]

Does anyone know to what degree nose art and the like has been tolerated among American aviation throughout history? I know plenty of examples exist, especially from World War 2, but existing doesn't mean being allowed, and I don't see it being tolerated in today's armed forces. Was it ever allowed? If so, when was it banned? If it was never allowed, how commonly was that rule broken, and when did it become universally enforced?

Doing a bit of digging, it looks like nose art, especially the racy pinup, started being phased out during the Korean War, mostly due to changing military policies and attitudes towards the representation of women. It saw a bit of revival during the Vietnam War, with the AC-130 gunship unofficial badge of a skeleton with a minigun being adopted formally.

During Operation Desert Storm and Enduring Freedom, crews have been including the art as part of a camo pattern, and USAF have unofficially sanctioned nose art of clothed pinups on their bomber force, with strong encouragement of continuing historic names like Memphis Belle.
I found reference to a 2015 USAF memo, where crews can apply for permission for nose art, provided it is "distinctive, symbolic, gender neutral, intended to enhance unit pride, designed in good taste, and abide by copyright and trademark laws".

Spoiler: F-16 Falcon deployed in support of Operation Enduring Freedom

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Spoiler: Boeing KC-135E Stratotanker, based with Sioux City Air National Guard, 2007

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Spoiler: A-10 Thunderbolt II during the 74th Expeditionary Fighter Squadron’s deployment to Graf Ignatievo, Bulgaria, March 18, 2016

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[Yora]

Are there any well documented and researched examples of major wars in which both sides were using guerilla armies? Does that even work or is it a response to facing technologically and numerically superior enemies?

[Vinyadan]

When I was a child, I had a toy A-10 with that decoration.

I have been reading Machiavelli's Discourses about Livy. Among other things, he reports Livy's description of the old Roman system of principes, hastati and triarii. This comprises that somewhat odd description of their formation, in which the second line kept its ranks loose to allow the first line to merge into it if things went badly, and the third line was even looser to allow both lines to merge if forced to retreat.
The commenter said that Livy probably took these descriptions from a work of Cato Maior, and that they must have referred to some exercise, and not to a normal order of battle. However, while denying the reality of this practice in battle, the comment does not address how this exercise impacted battle performance, which I guess is the purpose of all military exercises.
Right now, my theory is that it was a way of showing soldiers how to handle it, if the men in front of them were forced to retreat, as to avoid two things: first, sandwiching the retreating first line between the advancing enemy and the back lines, when they couldn't fight; second, that the retreating first line would have impeded the ones behind it, stopping them from advancing and from joining combat, possibly weakening the formation and causing danger or defeat.
So, in practice, I think it was a way to teach the lines how much room they needed to create between each man if need be, and to teach the officers to be on the lookout and ensure that the line did have enough room to widen.

Are there some modern studies of how the system would have been applied, or, generally speaking, some educated guess?

[Kiero]

When I was a child, I had a toy A-10 with that decoration.

I have been reading Machiavelli's Discourses about Livy. Among other things, he reports Livy's description of the old Roman system of principes, hastati and triarii. This comprises that somewhat odd description of their formation, in which the second line kept its ranks loose to allow the first line to merge into it if things went badly, and the third line was even looser to allow both lines to merge if forced to retreat.
The commenter said that Livy probably took these descriptions from a work of Cato Maior, and that they must have referred to some exercise, and not to a normal order of battle. However, while denying the reality of this practice in battle, the comment does not address how this exercise impacted battle performance, which I guess is the purpose of all military exercises.
Right now, my theory is that it was a way of showing soldiers how to handle it, if the men in front of them were forced to retreat, as to avoid two things: first, sandwiching the retreating first line between the advancing enemy and the back lines, when they couldn't fight; second, that the retreating first line would have impeded the ones behind it, stopping them from advancing and from joining combat, possibly weakening the formation and causing danger or defeat.
So, in practice, I think it was a way to teach the lines how much room they needed to create between each man if need be, and to teach the officers to be on the lookout and ensure that the line did have enough room to widen.

Are there some modern studies of how the system would have been applied, or, generally speaking, some educated guess?

Livy makes stuff up and really doesn't understand military affairs (even though Machiavelli did understand them in his own time, he's reading someone who wasn't a soldier). If you want to know anything about the Roman military, from someone who was both a soldier and general, and indeed fought the Romans, read Polybius.

[KarlMarx]

When I was a child, I had a toy A-10 with that decoration.

I have been reading Machiavelli's Discourses about Livy. Among other things, he reports Livy's description of the old Roman system of principes, hastati and triarii. This comprises that somewhat odd description of their formation, in which the second line kept its ranks loose to allow the first line to merge into it if things went badly, and the third line was even looser to allow both lines to merge if forced to retreat.
The commenter said that Livy probably took these descriptions from a work of Cato Maior, and that they must have referred to some exercise, and not to a normal order of battle. However, while denying the reality of this practice in battle, the comment does not address how this exercise impacted battle performance, which I guess is the purpose of all military exercises.
Right now, my theory is that it was a way of showing soldiers how to handle it, if the men in front of them were forced to retreat, as to avoid two things: first, sandwiching the retreating first line between the advancing enemy and the back lines, when they couldn't fight; second, that the retreating first line would have impeded the ones behind it, stopping them from advancing and from joining combat, possibly weakening the formation and causing danger or defeat.
So, in practice, I think it was a way to teach the lines how much room they needed to create between each man if need be, and to teach the officers to be on the lookout and ensure that the line did have enough room to widen.

Are there some modern studies of how the system would have been applied, or, generally speaking, some educated guess?

The Manipular formation, probably what was loosely described, consisted of velites, hastati, principes, and triarii being arrayed in a "checkerboard" pattern, which was mostly used for maneuvering. Each type of troop would form a line of alternating maniples (~200 men) and gaps, with each gap being covered by a maniple of the infantry behind. Again, this was mostly used to move through difficult terrain--especially after the defeats of the early Samnite Wars--and in battle the troops would form solid lines in the same order. However, Manipular formation could also be used in battle, especially against light troops in rough terrain where battles quickly devolved into small unit actions, meaning that the maneuverability to deploy quickly trumped the necessity to maintain a solid line.