Not just a myth here but also then spread by many historians. Yes navies were important, but not that important during the start and late period for the regular supply.
It wasn't. Food preservation really suffered in the time period and the easiest method was local supply as it would be freshest and also cheapest. Then add in that most nations didn't actually have navies for the start of the game with most ships being owned by private individuals.
Armies don't need to live off the land for ever. They weren't being sent to stand in one region for decades, they were generally on the move and would only rely on supply lines on the local level due to them being able to go at similar speeds, they can't rely on ships as there's not rivers and ports located everywhere. They haven't got the manpower to send back to protect a long supply line with the food slowly rotting and getting spoiled.
Yeah forts were important for the local supply, it was an easy way to locate a range of stores for the campaigns, but again they weren't shipping those goods to the other side of the nation when they could get it from a fort nearer. We have the issue that forts aren't as common as history in game. Similar ways we have issues of the scale of armies ramping up to insane numbers.
Not really, Napoleons invasion of Russia is a good example that it was well known even late in the period that armies relied on local sources of food, why scorched earth tactics has been used through history and was wide spread in the time frame EU covers. But the bigger thing with Napoleon is that he is well known for not having a very useful navy. He had rather large issues getting it out of port and do anything useful. Yet his armies were extremely effective.
Yes it's easier to supply via ship, but only if you are near navigable water with a large enough dock to make moving the supplies easier. It wasn't practical for most of the period and is often shown as having huge issues, they didn't have fast paced communications between them making linking up a pain. This is why their main use is more for the initially transport and is from established coastal towns/cities. Existing infrastructure and generally if chosen friendly enough that you can also pick up more supplies.
Just before the time period Hawkwood Diabolical Englishman often covers this, it's set mostly in the 1350s-1380s mostly in Italy with the wars between the city states, forces often running out of supply mostly in winter and having to retreat back to their backers. They couldn't rely on supply convoys over such a short distance, neither boat nor cart for the most part. One mention of them using ships to supply a stronghold on a river, wasn't ocean going ships but local merchants. Navy would make 0 impact to that. We do have his small force repeatedly looting the area however, in one account raiding a small area and coming away with over 8,000 heads of livestock, estimates of his force being 2,500 which would be enough to feed them for a while. Rest of the time it was getting supply from a city/town and then taking it with them. in game that's the local province.
New Worlds and Lost Worlds, covers actions of the English during the Tudors. Army sent to pacify Irish lords who live off the land and a large part of their war is stealing livestock and crops, English claim to want to stop that to gain support and their army goes around stealing the crops.
We then have the British in the revolutionary war/American War of Independence, Britain tried to establish food shipments for it's forces in America, it failed. They couldn't bring in enough food and of a worth while quality. This is a big part of the war, the British forces living off the land ended up turning people against the British cause and also opened their forces up more to being ambushed as foraging parties were easy targets.
We also have the French invasion of Egypt during the time frame, the French fleet getting destroyed and then their forces blockaded, Napoleon left 2 years before his remaining forces surrendered and that wasn't due to lack of supply but being beaten militarily.
I dont think you understood my point. I never said armies never resupplied locally (I specified that), just it wasn't just some kinda of norm that always applied in eu4 warfare no matter what and bc of that supply lines must not exist. That's the myth I'm referring to.
You basically proven if a war is quick and small, your army can live of the land without any big immediate problems. I never argued agaisnt that, I argued for the long and expensive wars that existed that armies couldn't afford by just living of the land.
You gave the example of the English armies during the 100 years war, I know them. They were very famous of just looting the french land and they basically had to rely on living of the land for multiple reasons. That's fair, I don't expect 1300 england to be able to supply their men with their low number of ships (on top of being small).
Well I can toy around and give another example that fits well into eu4 timeframe, the ottomans and siege of vienna. Even before the beguining of the march it was going to be a failure, due to the abysmal logistical nightmare and how long the supply train to support such army was.
The tactic of living of land also depends on the type of land, italian and french farmland are of course well supplied in food. But once again, a desert shouldn't be able to provide enough food for your army neither should an island or even a normal grasslands but no one lives there, so nothing to loot.
I think Imperator Rome supply system represents very well what I'm trying talking about with the supply train's and food, not perfect but a step in the right direction.
Now speaking about napoleon when I started by saying "napoleon strategy relied on living of the land" it is a good example of how armies would do that (I never denied that) but that isn't the point. The point I was making was that he had to use supply train's once that was no longer possible due to scorched earth.
His invasion of egypt is irrelevant, since napoleon is famous to rely of living of the land, and considering how rich egypt is in farmlands that's easy to see how his army "survived". He didn't need a navy to supply him.
Since you touched on the matter of merchant going vessels resupplying troops using rivers... I always felt those merchant ships are navies, they are ships after all. Kinda weird discounting them bc they are merchants vessels since they are still ships doing a job of resupplying troops very effectively by rivers. Convoys.
Well I acknowledge your examples of how navies "failed" or in others words didn't bring enough supply overseas in the american war of independence. But I feel it's a bit unfair this example, since by no means necessary could anyone resupply more than 30k men overseas at that time by just using boats. Due the ship technology and the fact Spain and France both joined the war (navy being a bit preoccupied). So by no means England was using all of it's power to resupply just those troops.
Ships supplied troops, if that was enough for the survival depends on a lot of things, but navies were nevertheless very important on military campaigns.
I dont see why this can't be simulated into eu5. The more technology advances with ship design, the more ships are capable to bring more supply overseas etc.
I see it a bit like supply train's work but by water (and better). On top of being a bit similar on how vicky navies are gonna work. It would add a different dynamic to eu5 navies and it's supply system.
Before I finish I want to talk about another example of Napoleon, this time one of his first battles after becoming a general. Napoleon instead of attacking the austria army that sieging an italian city, goes for the supply train's of the austria army. Basically causing the austrias to leave the siege and come to face napoleon army.