I don't see how proper stance and aiming of a rifle helps you properly wield a sword. Nor the reverse. Modern tactics are based upon the high-rate-of-fire and long-range weaponry available and technology-based support systems (mobility, communications). Just as older tactics were based upon similar factors.

How much do your modern era people know about logistics?

age appropriate items Interesting choice of words.

@PatriciaShanahan They know modern logistics, plus some living off the land. However raiding caravans is not exactly their cup of tea. Could you be more specific?

How many of them know how to ride a horse?

@user535733 Half a dozen. Few could use sword, a few could use bow

Although the Battle of Hattin was 87 years after Godfrey of Bouillon's death, it is a useful illustration of the importance of logistics, especially water supply. Saladin managed to maneuver the crusaders into camping overnight without access to water. Meanwhile, he had camel caravans bringing plenty of water to his army.

Something overlooked in these discussions is how useful the soldiers themselves would be, even without the training. A modern diet and training regimen means a way stronger and larger human - these guys would have a large edge when it came to raw power.

@PatriciaShanahan Logistics wouldn't apply in this scenario. The OP seems to be specifically asking about combat skills. Anyhow you would need a huge industrial base to support the logistical knowledge modern soldiers would have. There are somethings camels won't be able to replace just because we told you we need supplies to fight.

@Halfthawed I mean they are disciplined, literate, could read and draw maps, have battle experiences. Some of it should transfer, I think.

Actually, the whole 'map thing' could easily cut against them if the topography of the region changed in the 600 year or so time gap.

@PatriciaShanahan I don't know more details. All I have is interesting setting with plenty of jokes in my mind, and hoping to keep it somewhat realistic.

@Ravmills: They are most definitely not literate in medieval latin (it doesn't look at all like modern printed text), there are practically no maps to be read, and they certainly have zero medieval battle experience. They don't know how to behave in society, they have the wrong religion (even the Catholics would be perceived as horrendous heretics by 10th century people), they don't know the price of everyday stuff.

”age appropriate items” ... I was thinking Nerf guns at first because that’s a particular phrase I usually see with kids’ toys! :-)

@AlexP I’ve actually had reasons to compare ancient and modern maps of the region. There’s not much drift in most natural landmarks— rivers changed course, mostly. But if these guys have detailed maps in their heads, I think that would be huge. ... particularly if one of them had ever compared against an ancient map even casually earlier in the story.

Another big issue in these types of questions (that often gets overlooked) is disease resistance. Should their antibodies are sort of hand-wavily transformed too? Like, if we want to be really pedantic, we could assume they have the sort of vaccinations that the military would give them if they intended to send them back in time (so, not automatically immune to all illness, but still significantly superior to the baseline for the time)? And that they aren't carrying any particularly nasty stuff back from the future?

can the soldier create gun or teach the crusade about gun technology ? even basic gun would do, but honestly. this soldier is far better as crossbow unit even better if they know how to create pavise shield as mobile cover if they engage in field or siege (as attacker) even better if the soldier know how to design something like automatic crossbow or at least repeating crossbow

It not whats on them that made them deadly but whats on their mind! ;D

godfrey also means God-fear in french, from the root of affray.

@Zwuwdz They don't bring any germs, nor are more or less susceptible to diseases.

@LiJun No technology stays the same.

so do you want them to be melee specific or crossbow is ok ? since in my opinion the soldier would do better as crossbowman units, make more sense that their weapon turn into crossbow rather than sword or spear anyway. and this require even less training even peasant can use it.

@Halfthawed Not so much. Strength is nice to have, but it isn't an alternative to skill; and when it comes to them not getting stuck with the pointy end, skill is very much your friend. There's also a large element of "sport-specific muscles" involved which they won't have.

@Graham On the other hand, a whole lot of warfare is moving stuff around, and the extra strength could help a lot there - if you're stronger, you can dig fortifications faster, lug more supplies around, etc.

You say "technology stays the same." Gunpowder had already been used in combat 200 years before the time you are talking about and you can be sure that at least a few of the soldiers would know that a charcoal, brimstone and saltpeter can be mixed to make explosives. And that is assuming that you are throwing a random group of soldiers into some "time vortex" without any warning. If they knew they were going back in time they would be sure to "cram for the test" so to speak and would have a much larger amount of knowledge available.

I'm tangentially reminded of Robin Hood (2018) and that movie's bizarre find-and-replace method of putting medieval equipment on modern combat situations.