By level 5-6 d&d characters are approaching the upper end of what's humanly possible (and in some cases go beyond that), so if it's humanly possible odds are a 5-6th lebel character can do it without significant trouble.
That's quite exactly my point. The 56-mile march on a 80 pound load in three days is nothing short of amazing. But i have some gripes about the way D&D rules carrying weight, though.
By the table, 80lbs is medium load starting at STR 12.
Have you ever tried walking around with 36kg of stuff strapped on your back? I mean, most fit, tall and really strong athletic man are on the neighborhood of 90 to 110kgs. That's more than a third of his body weight.
Regardless. Let's get to brass tackles.
In D&D, having a medium load puts you at 20ft tactical walking speed if you're human, meaning you do 2 miles per hour when you're on a forced march. Now let's try and apply that to our example.
The men marched 56 miles in three days. Let's assume it was a medium load for them (not a light load).
Means 18,6... miles per day. Applying the table to the situation, means the men, were they in the world of D&D, would only needed to have marched 9 hours and 20 minutes per day to reach their goal. Again, that's assuming 12 strength. With D&D, we see that 80 pounds starts being a medium load on 12 str for a biped, anything less than 12 and it's a heavy load, and starts being a light load on 17 str.
What that means? According to the rules of D&D, they would've had to make exactly 2 checks at DC 14, one for the first hour and the other for the second (incomplete) hour.
Well. If they have 12 str, doesn't hurt to assume they have 12 con too, right? Let's also assume that they didn't fail a single check, because they had to be fit for combat as soon as they got where they're going.
What consists of a Spec Ops super-badass dude? Certainly not first level. Let's take the warrior and assume a 4th level character, just shy of breaking the barrier of "common dude" and entering "hero" territory. Let's pick Warrior as our class.
At 4th level a warrior has +4 to fortitude. Adds the +1 to Con. We get to +5. So they need to roll a 9 or above, giving them a 60% chance of beating the save. Since it's three days, they have to make, total, 6 checks, each at a 60% chance.
That's 4,6656% chance of getting there, without failing a single one of the six saves they were to make.
But these guys, IMO, these SpecOPs super badass dudes, i don't see them at 12 str. 12str is 1 or 2 points removed from a normal, simple commoner. I don't see them as 12 con, either. This thing they did? The 3 day forced march? That's kind of a common occurrency in armies, even now, and even MORE so way back in medieval times.
I don't see them succeeding only 4% of the time. If they really are to be elite SpecOps super badasses, they'd have to get that to an 80% chance at least, which means 4 more points in fortitude coming either from levels or from even numbers in Con. Hell, if they're that super badass, an Elite Array is enough to really represent them? The cream of the crop of the military all over the world? Or should they get at least a 25pb?
I think after this thought exercise, the rules on forced march may even be
rough compared to what real world soldiers have to go through, both in boot camp and in active duty. I leave my findings here for the discussion to continue. I'll return later and see what we can come up with, collectively.