Total war may have been the exception, but farms and cities both suffered enormously during pre-20th century European warfare. Indeed the page you linked gave a bunch of examples of total destruction prior to the 20th century.
Outside those examples, most warfare then relied on looting farms for supplies (including seed crops)[1]. Indeed there was a whole technique of warfare called Chevauchée which relied on this before the 14th century:
A chevauchée [..] was a raiding method of medieval warfare for weakening the enemy, primarily by burning and pillaging enemy territory in order to reduce the productivity of a region, as opposed to siege warfare or wars of conquest... The chevauchée has gained recognition for its use during the Hundred Years' War between the Kingdom of England and the Kingdom of France. It was not a new tactic and had been used many times before; for example, William the Conqueror had used the tactic before the Battle of Hastings to encourage Harold to engage in a battle.[2]
[1] https://en.wikipedia.org/wiki/Medieval_warfare#Supplies_and_...
This varies very much on the "something". In the case of a virus like this I have plans to do what seems sensible - keep washing my hands, isolate myself as much as possible.
In the case of a war I'll hope my side wins and keep my head down if it doesn't. Not sure stockpiled ammo is going to be the critical factor there!
But if it makes you feel better…
What I mean is that evidence shows that when a society collapses, the corrupt and evil will explicitly use the state's monopoly on violence to take what you are trying to defend.
Typically they juice this by exploiting local grievances to de-ligitimise your claim to your property and co-opt the local law enforcement with promises of future gains.
Then they will appear at your homestead WITH the local enforcement - who will do nothing when the mob takes yours assets.
At one level this is to discourage you and increase your sense of isolation - to get you to just abandon your assets and leave. At which point they move onto the next property/resource owner.
However, at another level they WANT to to fight back - with firearms preferably. Not only will this still be deemed illegal (under laws passed by the old functioning society) but hopefully (from their perspective) you injure or kill one of the riled-up mob - further de-legitimising you.
At this point, the co-opted law enforcement will step in, arrest you, etc.
Zimbabwe, the Balkans, and Indonesia are text-book examples.
When society fails violently, there really is no hope.
I wish it wasn't thus, but is is and will be.
The U.S. was founded on rebellion. And I believe enough Americans would readily backstab an illegitimate U.S. government (one that has stopped serving its people and instead serves itself) in pursuit of good.
FTFY
2.The U.S. was founded on rebellion.
So was Somalia. Its not a sufficient reason to protect you from the failure mode I explained above.
I don't have an answer for this, but it's something worth keeping in the back of your mind when discussing theoretical catastrophes.
Sit back and wait for the state to save you? I'm not American myself but the lack of self-reliance exhibited by non-Americans, particularly Europeans, is sometimes bewildering.