Are rural residents more likely to survive large scale war (> 1 million deaths) than urban residents? (Data based answers only)

Military Armies don't target "Urban Areas Only". Rural Places are just as Targeted as Urban places. Covid-19 is a virus, not a Military General. Capturing a Capitol is necessary for collapsing a country, but it is illogical that it would itself collapse the entire country.

During World War ll, the Germans went everywhere just to Exterminating jews. Jews are not safe in the rural German Villages. Armies need to find a way to get to their "Urban Target" by entering through rural towns in bad weather, Sicily for example was not Urban

Covid-19 is a health issue, it does not determine which town an Army will invade.

Depends on geography

Less examine various types of settlements :

• Mountain village . In Europe, very common in Balkans (Montenegro, Bosnia, Serbia, Bulgaria, Romania, Greece ... ) . Also for example in Georgia. Why would anyone want to settle high up into mountain, far from major roads (or any roads) in wilderness ? Well, precisely because of that. Christians living under Muslim Ottoman rule had a very hard time. High taxes, subjugation to local Muslim feudal lords, plus occasionally looting, burning, raping and killing by marauding regular or irregular Ottoman troops. Solution ? Move high into mountains, far from roads where larger armies would pass, in fact somewhere where only locals would know narrow lanes leading from one village to another. If some relatively minor gang of pillager decide to take a chance, you could (alongside other villages) organize an ambush in suitable location with your local knowledge and greet attacker with hot lead. History of Montenegro was full of such examples. And even if larger army (rare event) decide to go and punish rebellious mountain population, you would have ample time to flee into forests until the danger passes.

• Village in flat lands If you live in a village situated in plain, then your situation is pretty dire. These villages were usually without fortifications and permanent garrison, or at best had wooden palisades with few troops. In case of any larger invasion, you could count on village being pillaged and devastated. What is even worse, without some large forest nearby you stand no chance of escaping attackers on fast horses. Glaring example of that is First Mongol invasion of Hungary where unprotected population in villages was devastated (50-80% of settlements destroyed, 15-25% of total population killed ). This also repeated in subsequent Mongol and latter Ottoman invasions. One other good example is Mongol invasion of Russia. Generally, not a good place to live during invasion.

• Fortified towns and cities. Mixed blessing. Richter and more important towns would have stronger fortifications, better food storage for the siege, better chance of relief army coming to end the siege. Unfortunately they would attract larger invading armies trying to conquer them. Those armies would be prepared for long lasting siege (months, sometimes even years) and would have various siege machines and specialists. Life in a city under siege could became very harsh. Of course, some cities like Vienna were lucky to endure the siege. Some like Constantinople fell and endured tens of thousands of murders and rapes, not to mention enslavement and pillage.

• Mountain fortifications. There were attempts to combine fortifications with a shelter of a mountain. These were usually castles or monasteries built deep into mountains with some fortifications around them and small garrison. Sometimes they were surveillance outposts like for example Belogradchik Fortress. Again, security of the fortification depended mostly on its strategic and economic value. More valuable fortifications would attract larger invading armies and would fall. But, they could certainly defend themselves against minor raids, and similarly to mountain villages had option of fleeing into mountains at approach of lager enemy host.

So what is a final conclusion ? If you are interested in statistical analyses best advice would be to seek percent of rural and urban population in a given country during certain period. Since survivors survive :) if you have large population of villagers that means your villages are relatively safe. If, like in the case of Hungary, you suddenly find yourself practically without peasants, that means that your villages are highly vulnerable.

The Thirty Years War is estimated to have killed about 40% of Germany's rural population and around 20 to 30 of the urban population (33% of the urban population according to a source cited in this article).

Such estimates are a bit difficult because in the past, population data was often gathered for tax purposes, so there were incentives for not beimg counted and it also made sense to just ignore those who were too poor to pay anything anyway (argued e.g. here* for the Thirty Years War). I believe it is also quite difficult to account for migration/displacement, which tended and tends to happen a lot during wars.

_{*That article also nicely supports rs.29's point re. out-of-the way villages. The Oderbruch area at that time was a giant swamp area and the historian cited in the article says that population losses there were a lot less than in some nearby areas.}

It's logical you can't find hard data, because your premises are flawed.

Look at medieval cities. What do you notice? A city wall. That's what separated the sheep from the goats, in this case: cities from villages. Walled cities offered protection not only for their own citizens, but also for the surrounding countryside.

That distinction was pretty important back then, and even now. A city was defined by its walls. Not having a wall made it a large, or very large village.

Assuming the city fathers had a bit of forewarning and common sense, they had stocks of food available to withstand a siege. Not always, for example the citizens of Haarlem suffered starvation because their city fathers didn't think a siege was going to happen. In many countries, the city was the official refuge for country folk of the surrounding area.

That's taking care of the food and safety issue. Towns were safer than villages. A lot safer. Let's have a look at that now:

Villages were prime targets for roving military and other bands. There was some wealth, not a lot, and probably some food to be found there. As well women to be raped. Few villages had a wall or even a stockade. As well as far fewer citizens available for defense.

In defense, numbers do add up. A city is not only safer because it has a wall. Per m2, it has far more people than a comparable village. Even if a village is protected by a stockade, rarely there enough defenders available to properly man it.

Most armies in that period lived off the land. Which was: the countryside. They took what was available, and then some more (very often). Both military bands or units and opportunistic bandits. They had little chance to lay successfully siege to a town, but pillaging a village was their bread and butter. Very often, literally.

After you completely changed your question, you added:

My primary interest in this is developing an accurate predictive model for the future.

That is impossible. Medieval warfare cannot be compared with modern warfare. Even if you would try that, the basics remain the same: modern cities are notoriously difficult to attack and easy to defend. Look at Stalingrad, Cherbourg, Warsaw and many other cities. The countryside wasn't much better of, in many cases villages were burned to the ground. That happened a lot during WW2, as well as during following conflicts.

Your next points about NBC weapons I won't address because they are completely outside the topic. Actually, because of that, I have to regretfully downvote your question.

With regard to your question, your best bet is to dig in what is happening in Syria right now. It meets all your requirements.