Secondly, before you read any further, understand that the philosophy for which I'll be laying the groundwork throughout this series will be best geared toward the less-likely but always possible TEOTWAWKI (The End Of The World As We Know It) "New Dark Age"-type scenarios often discussed. In short, we won't be going prepper-lite, discussing the finer points of storing enough canned-goods and candles to get you through a bad storm, layoff from your job, or other temporary situation. In these articles, we'll be going full-on Mad Max, complete with roving gangs of raping and pillaging Mutant Zombie Bikers (MZBs). So, you know, prepare yourself. Sometimes it helps to adjust your mind-set before delving in to a thought experiment such as this one.
Without further ado...
Many in the survivalist/prepper community favor a philosophy of gaining safety by staying out of sight. In fact, this is probably what a lot of people will be stuck with even if they don't particularly like it, because of economic reasons. A cabin in the woods will keep you safe (and leading a woefully isolated existence, I might add) as long as you stay hidden; but if some enterprising troupe of hooligans stumbles across your happy little hidey-hole, you're likely in for a bad day.
I've been telling friends of mine forever that, if I ever hit the lottery or somehow otherwise get filthy rich, I'll be building a castle for my home. A real one. Towers, high walls, moat and drawbridge -- the whole works. Call me eccentric, I guess. I meant it too, but, alas the riches have thus far avoided me, so it's a plain ol' boring retreat homestead for me too. However, in light of the very real concern that any discovery of our isolated hideaways might cause us all to catch an incurable case of dead-meat-itis (and because few of us are wealthy enough to build our own castles), my take is that:
1.) Building with masonry trumps wood for stopping bullets and resisting fire damage. This was true for medieval castles and it's true now. What most people don't know is that most castles were originally wooden structures with the stone added later, either after the inhabitants got good and settled or after someone burned parts of it to the flippin' ground and they wisened-up. Castles eventually became militarily-obsolete because of artillery, but, if you're fending-off looters or the Crips or the Hell's Angels, I doubt they'll have a tank to throw at you (and, if they do, you're screwed anyway!)
So, in short, do whatever you can to adopt a castle-mentality. Sandbags full of dirt will also be useful for such purposes, though, less so than masonry. Basically, your goal should be to present a hardened target, resulting in your attackers deciding that killing and robbing you will take too much time and result in too many of them getting dead as well and consequently moving on to other riper fruit, as the creepy saying goes.
2.) The higher the position the better -- if not your domecile/property, at the very least, a look-out station. The army calls this an LP/OP (Listening Post/Observation Post) and there's a reason it's a tactic that has been utilized militarily for thousands of years. I already have spots picked-out for three of them around my property that, if manned, would provide commanding views of every major lane of approach. I suggest you do the same.
3.) If attacked by a large force, *DO NOT* waste resources by trying to defend every square-foot of your property, but, rather concentrate on defending a small central hub (likely, you're actual home). In a castle this was called the keep, and it usually contained the lord's private residence; cisterns for water storage; granaries and food storage; stockpiled weapons (an armory); and space enough to hold a large number of people in times of distress. Smaller equals easier to successfully defend. If they burn your barn and whatever crops are in the ground, you can rebuild and replant after the trouble has passed. There is a long proud tradition built around people getting their arses behind a thick wall and waiting for the bad guys to go away.
I'll add to that by saying, with respect to livestock, select breeding pairs should be picked-out ahead of time, so that they too can be saved with short-notice to rebuild flocks, herds, etc. It may sound crazy to you to have chickens and goats indoors, but it's precisely what people did for thousands of years. Entire herds, aside from breeding pairs were slaughtered every October to avoid having to try to keep them alive over the Winter; modern-day Halloween coincides with the pagan festival of Samhain that was also called Blood Harvest, just as there were festivals to mark the first and second harvests of the growing season. It was called Blood Harvest, because of all the slaughtering, in case that wasn't obvious enough. The breeding pairs that were spared often spent the Winter right alongside the family. People even brought their milk cows inside during the harsh Winters. Of course, they had dirt floors -- I would not advise bringing a cow into your living room with today's construction. ;)
4.) Food/water supplies must be protected, at all costs. This is a truth that gets beat to death on survivalist sites, but human beings can only survive about three days without water. If you have thousands of gallons of water storage, kudos to you; if it's in above-ground tanks a hundred feet from your house, consider yourself as having exactly zero gallons. Ditto with a well. If you're holed-up inside your "castle" safe and sound, but under siege for any significant amount of time, what the H3ll good does that do you if you have no water to drink or cook with? Even if your attackers leave, what's to keep them from destroying your tanks/well equipment or fouling your supply as a final F U before leaving? Food is a topic I won't beat to death, because it's self-explanatory: follow basic survivalist/prepper guidelines with regard to storage food. But, the moral here is that it needs to be stored close where it can be better protected.
5.) Every serious survivalist should watch "The Outlaw Josey Wales" for tips on how a small force can outlast a larger one from a well-defended fixed position in a fire-fight. If you haven't seen it, do; but, in the meantime, just know that what I'm referring to specifically is where the characters fend-off an attack from within a Texas ranch house that was previously fortified to withstand Indian raids.
I think that covers just about everything from the standpoint of proper fortifications. Undoubtedly, I'll think of something else I wanted to add after I post this, but it's already a long article, so it'll have to suffice. As always, thoughts/critiques/concerns, etc. are welcomed in the Comments section below.
Some reading (pertinent to this subject) that you might enjoy:
"Patriots: Surviving the Coming Collapse" by James Wesley Rawles
"Survivors: A Novel of the Coming Collapse" by James Wesley Rawles
"The Medieval Fortress: Castles, Forts, And Walled Cities Of The Middle Ages" by J.E. Kaufmann & H.W. Kaufmann
"Survival Retreats: A Practical Guide to Creating a Sustainable, Defendable Refuge" by David Black
"Life in a Medieval Castle" by Joseph Gies
"The Survival Retreat: A Total Plan For Retreat Defense" by Ragnar Benson