Shields - Round vs Heater

At about 24", I think it's a matter of fashion, if on foot. If mounted, the shape probably matters for comfortable and easy carry (for that size and up; if the shield is smaller, then I don't think it matters).

Points on a heater allow an opponent to try to twist your shield around with a long weapon, and a heater is easier to hook. A heater blocks your vision a little less.

It's at the large end for forearm-strapped dhals and Scottish targes (and the centre-gripped versions are smaller). About standard size for Renaissance rotella. (And normal for round riot shields, which I think are more melee-oriented and less for missile defense than the big rectangular riot shields.)

Don't know of any forearm-strapped round shields of about 30" (Greek hoplite shields were much bigger than that); that's a common size for large centre-gripped round shields (Dark Ages, Viking). Perhaps this is a bad size for protection vs bulk and visibility for forearm-strapped? I wouldn't be surprised if that's the case - I find a 24" round shield is good against melee weapons, and I never felt I wanted a bigger one. (Missile weapons might make me want a bigger shield.)

Throat to groin looks common for length of heaters, with a few bigger and lots of really small ones. 24" by 30" heater might be pretty normal. Which suggests one reason for the heater is to have more shield without more width.

I know far more about this than I like to admit.
The reality is...it depends.
IMO for equivalent protection, you'd need a larger round than a heater if we're talking arm strapped. The styles would be very differnt as well.
Anyhow, it also depends on what you're fighting and the styles used.
But in general, the heater works well with heavier armors, and in later styles you see more rounds with lighter armor, but then the styles were dramatically different.

So in summation, in this case, you'd at best be arguing what's a better food...apples or fish?


Though if you wanted to be scenario specific to styles and armor, just look at historical references for guidance on what worked better, because there's a reason they did things *that* way...we may not know why...but there was.

Nods.
This goes back to the 'it depends' portion of my thought.
I do know in SCA fighting (which is really goofy and a-historical) that when I used a 24" round, I had to be very active with it, much like using a buckler in energy expenditure to guard myself during fights. When I kicked it up to a 32" round, the weight was prohibitive and it actually got in the way...lots.
I like Heaters for lower energy defense, but it still depends what and who you're fighting.
The real answer? Drop a nuke from space, its the only way to be sure.

It's tough to say how any of these were used and therefore difficult to know what the advantages and disadvantages are. As far as I know, no training manuals survive with much detail prior to I.33. The center-grip shields seem to have been used pretty actively, and at this point I'm persuaded that Roland's interpretation makes a heck of a lot of sense. Though it may be too close to buckler techniques he's worked on and contain anachronisms as a result. The weight is an issue as well. How heavy were the actual historical shields? Does anyone have a complete intact example to weigh? This was a major confusion re. medieval swords back when few people had bothered to actually figure out their true weight. So we got the pernicious Victorian myth of the huge, dull broadsword bashing into armor mindlessly. Could shields made for combat actually been far lighter than we have recreated them? As in no more than perhaps three or four pounds?

But OTOH you do see many illustrations of knights standing behind rather passively-held shields that seem to be pretty bulky. And both arm strap and center-grip shields appear to be used both actively and passively. I suspect there's just too much we don't know about how they were truly used. Form always seems to follow function, right down to the precise curve of a crossguard or the width of a blade. Everything they did seems to have had a martial reason. I'm thinking specifically of the Type XIV, which might have initially been seen as a decorative short sword but turns out to have been made precisely for certain types of combat right down to specific overbinds and counterstrikes.  

Personally, from all that I've been learning of early longsword and s&b, I think any system designed around purely passive defenses was doomed from the start and never would have caught on.  All these arts focus on the offensive.  Taking the vor and keeping it.  Killing the other guy before he kills you.  None of them have any regard for standing behind something blocking up or down.  And that kind of reactive, passive defense is almost suicidal given the tools of the day.  So I don't put much credence in the notion that shields would have been simply used for passive blocking.  Blocking gets your attention on the blade and that always gets you killed.  Well it gets ME killed anyway! You have to focus on the other guy and have plans to end him as quickly as possible.  Which is a roundabout way of saying I don't think the strength of any shield design came from covering more territory where blows could come in from.  I think its strength would be in controlling the critical center in order to stab or cut the other guy without getting stabbed or cut, as it is in every known blade combat system right up through the 19th century.  And I think the shields would have had to protect the hand of the swordsman in the process.  In light of that, I can see advantages to either a round center-grip design used in Roland's method or a kite shaped arm-wrapped design used offensively to shield strike and pin the enemy's blade back.  I'm imagining a 12th century knight keeping a close guard as he approaches, then exploding out with a combination of overbind, shield strike with the edge of his kite aimed right at the center of his foe's chest, slight sidestep as he presses in and delivers a killing blow. Assuming his legs had protection against cuts, he would be able to afford to keep his shield closer to his torso in exchange for the added leverage of his double strapped forearm. I'd like to test this, but my bet is with a strapped-on kite design and the right footwork you could not only neutralize a foe with a strike to his center, you could spin him around or even drop him down on his face.  It puts all of your torso strength directly into the shield--as opposed to a centergrip or buckler which relies on weaker shoulder muscles (as my left shoulder is now reminding me)

One thing I can confirm from the re-enactor community is they tend to have completely unrealistic expectations about shields and armor durability.
My completely unscientific research has shown shields were lighter and cheaply expendable. So for Viking rounds, if it lasted a hit or three, it seems that was about expected (from saga resources). How much damage it could actually stop, is infinitely debatable.

So I still fall back to: what are you fighting against, and what is your body mechanic. From a practical point of view, considering all shields unbreakable, and everyone wearing the same armor, it really is about *your* body mechanic and what works for you.

Now if we're talking fantasy book, and *Miraculum* shields, well....

I do pretty well with a coffin-kite at 42"x24" at the greatest measurements in a forward, aggressive style. And equally well in a shield wall.

It all depends on your personal body mechanics and mentality. My fighting with sword and shield is based on my unarmed kung fu and my mentality is aggressive defense. IOW, I will shove my defense in your face and let you eat it while I beat the crap out of you.

Other people have different styles and mentalities and use the shields they find best suited to them.
Or, just as often, the shields they can find people to teach them to use. It's a long, slow road, figuring out on your own how to use a shield. And it involves getting hit. A lot.