Elyrian war tactics
Okay, so, this is going to be a long post, and as a strategy buff i might get a little carried away, but if you are any kind of army owning elyrian this might help you.
To clarify in this case i'm referring to:
"Modern" as first and second WW
"Medieval" from fall of rome to Industrial revolution(focusing in europe for simplicity as asia had more of a ancient warfare as it had big empires that managed to hold)
"Ancient" 500 BCE to 500 CE roughly
Simplified (And probably full of errors) explanation of this three types of warfare that you could want to skip
Ancient warfar
Iin the case of SPQR for example, had a well defined chain of command, with bottom up and top down charges, standard division size, standard army size(cohort) , standard unit class with standard equipment, also had armies so big that it was able to do construction projects as building a fleet(first roman incursion into britania by julius caesar) Regularly making massive ramps to walk into walls, and often besieging whole cities (armies got into the tens of thousand and more) They had messenggers, foraging teams, and would even carried wooden walls with them that could quickly become a fortified encampment.
All in all, a disciplined army that was trained and managed directly by the empire.
Medieval warfare
After the fall of rome, any kind of central state disappeared in europe, so a localized type of army become common, a local "nobles"
(everybody who owned land and was able to lease it for a good part of the production but also offered protection to the people that become "Serfs" and where tied to the land of this land owner)
As local nobles become stronger, they started to exert control over neighbouring nobles forcing them to help them in battles and pay a tribute, this waker nobles become vasallegs, barons counts duques, and the powerful one become king(kinda)
Decentralized army that was able to work without any central power in place, and no need for officers, generals or bureaucracy in general, as the vasallegs would take care of all of that, All in all, small armies that could rally into one big army for some time, but were hard to keep organized as each noble could try to be its own army, and could decide to leave and would be hard to force back into the war.
Modern warfare
Basically to just talk about what matters to CoE, the focus changed from defeating the army and taking the castles, to actually destroying and taking the production lines of the enemy to stop its war machine, things like gorilla warfare, organized resistance, encirclement, mobile warfare, and wars that took millions of deaths, instead of thousands. Every inch of the border has to be protected, and so all the frontiers became frontlines. also supplies, and supply raiding become really important.
END of explanation
So, event tho this systems were a product of the technology, resources, and government structures of the specific times, they were, as everything else, a discovery, many of the modern warfare strategies could be implemented into either ancient type armies, and medieval armies, the ancient armies actually share a lot of things, and if you were to use the magic on the internet you could gent modern times types of armies(more on this later), but i think i focus on delay and archer fire with a constant supply of arrows could breed an early type of musket squads of the XVII century were the ranged do all the damage, and infatery is there to protect said archers, with field forts and such, could dominate completely poorly armed armies, and this armies could be counteracted by heavy mobility armies that could cut said arrow supplies. Mobility armies could also encircle an enemy using firepower, fortifications and terrain to dissuade said army of trying to breakout, ensure attrition to those men, and allowing for a complete wipe out of that army(that considering the really big manpower pools of Elyria would be more for the equipment than the deaths): and things like city raids for more decentralized and medieval armies, guerilla warfare, and deviant cooperation, like privateers.
About the magic of the internet
This is something i think should not be used, but, when big kingdoms clash their costly lands into each other one can only expect them to do whatever possible to succeed, so organizing raids, resistance, ambushes, raids trough the internet could become normal in big wars(event tho all of this could be done less effectively without the outside help of the internet, and with a good messaging and maybe a good spies web )
To resume, i heard a lot of people talking about how battles would play, thinking that they would be just normal medieval battles, but the only reason games like total war have a meta that is similar to the one in medieval europe, its because they have restricted it to be like that, i think much more can be done, and should be done in CoE warfare.
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And as a strategy buff. if anyone is interested in a military advisor im up for grabs(?
Sources to check
For an example of more modern tactics on ancient times look at Historia Civilis on youtube,( i can only give you the video names, and battle name as i have to low influence, sorry) anything between Anibal Barca and Rome if good:
Battle of Cannae (216 B.C.E)
Battle of Lake Trasimene (217 B.C.E)
Battle of the Trebia River (218 B.C.E)
This two battles show the power of ranged troops
First one is Rome vs The Parthians
The Battle of Carrhae (53 B.C.E)
(here we see an encirclement of mobile ranged troops that have access to an arrow supply, beating easily an army that could counter arrows with the its heavy infantry, big shields and army formations )
And second a medieval war between France and England
The Battle of Agincourt (1415)
(were we see an early type of entrenchment, and the use of heavy piercing ranged attacks to counter heavily armored cavalry)
Also to see the example of caesar building a fleet:
Caesar in Britain (55 B.C.E.)
(the same channel of the videos "Historia Civilis" has many on historical pre industrial warfare, tactics, and politics)