I was looking through the many worlds that I haven't converted to 1.9 yet, I discovered a fort that was semi-built. I was inspired to try and finish it off making it as accurate as real forts from the early medieval era. The reason I say "early medieval" instead of "medieval" is because through-out the medieval era (~10,000 years) forts and castles became less about economics and holding territories but to show wealth and prestige.

Defences
The defences were required in the medieval era. Now? Not as much since if we build a massive wall over the country, a nuclear missile will still destroy us all. Every fairly populated, economic or strategic position had some sort of defence whether it be a small garrisoned force or a colossus wall.

Land
The terrain is one of the most important parts of a defence. It limits attackers' options on how to besiege the defended area. It can restricts the amount of equipment an attacker can bring. It can slow the advancement of armies. Some terrains are better than others.
Biomes
The biomes control what is available to use. For example a desert has less food and wood for the attackers which may limit the amount of construction the attackers can do and could cause rash decisions to be made which could end up with the defeat of the attackers. However a forest would have plenty of food and wood for the attackers allowing them to starve the defenders into surrender. Not only that but it gives the attackers a semi-shield from projectiles such as arrows. But not everything is against the defenders; depending on how thick the forest is allows the defenders to set up ambushes.

When a place is being built that needs to be defended, this should always be though about. But it is not just about defences. If we were to cancel the minecraft part of this, you would have to think of the more realistic problems too. Creating a castle or fort next to a river can not only be problematic for the attackers but also for the defenders. What if the river floods? What if the banks of the river collapse causing a wall to fall with it? What if the river dries up and the crops on the farms die sending the people of the area into starvation which would not only kill the peasants but also soldiers, nobles and the livestock. A place where people starve a lot is a place where people are slowly driven insane as they try desperately to get any food possible and when the attackers come with enough meat to last the next 30 thousand years (slight exaggeration) the people flock to them. Biomes like swamps and marshes have soggy ground that could flood so if something was to be made in these areas, it would have to be above the sea-level quite a bit to lower the chances of it being washed away.

The ground is also important. A place with soft ground (places with clay/gravel) can be infiltrated easier since digging a tunnel under the walls is effortless compared to trying to dig through hard ground like limestone. Something I see quite often is a wall that is meant to be super tough but them underneath it you can see some dirt. When a wall is being constructed it does not just sit on the soil! It digs deep within so it doesn't fall over the second the wind picks up. A biome like a desert is less likely to have hard rocks so big heavy walls wouldn't be made since they would fall over since the ground cannot keep it in the ground.
Terrain
The terrain is very important. An elevated position above the rest of the area can give great advantages. A steep hill will stop heavy things such as catapults and siege-towers from being able to reach the area as well as tiring out attackers who run up the sides thirsty for the defenders' blood. Examples of this can be seen in Norman castles (~1066AD+) when the keep is surrounded by a motte (often confused with the moat). If you are too lazy to build a motte then you can just find some raised terrain like I normally do and begin building there. Remember that defences are build to protect something, not to look fabulous.



Walls
Most important areas had walls or something with walls nearby. Walls had two main purposes; to protect what is behind it and to keep the things outside outside. Throughout history, (defensive) walls have gotten thicker and more advanced. During the Viking era they tended to be wooden unless it was a holy place such as a monastery but by the Napoleonic era, they were made of stone and very thick. It all depends on what is being thrown at the wall. Wooden walls were destroyed by fire so they became stone. Stone walls were destroyed by siege weapons. During that time, nothing that was cheap and stronger than stone was available so they just made the walls thicker. Then artillery came. This, over time, destroyed walls and caused them to be useless. That is why smaller things made out of concrete are used to defend, like bunkers.
Types of Walls
Despite most labelling walls as walls, there are different types of walls. European castles were incredibly basic and it wasn't until the 11th century when Crusaders returned from the Middle-East spreading the architectural skills. I think it's ironic how Europe was lacking behind but eventually became the creator of empires and lead the world into the industrial era. May we all take a moment to thank Royal Brittania.
Motte and Bailey
Motte and Bailey walls were wooden. They relied more on the terrain they're built on rather then them themselves. These are quick to build and very cheap but not as strong as stone and could easily catch fire.
Curtain Walls
Although these could also count as motte and bailey walls, these were mostly made of stone but were thin. It was not possible for anyone to "man the walls" with these since there is no place for them to stand. They can break easily but are still stronger than the motte and baileys.
"Castle Walls"
These are known as castle walls since they're thick, look decent (if well maintained) and people can stand on them. To see why these are the strongest, have a diagram.

The batter provides extra strength to the wall and sometimes rocks were dropped from the top to hit it. The angle of the batter would cause the rock to bounce towards the defenders which could cause casualties. The merlons were the parts of the wall that stuck up and the embrasures were the gaps in-between. Arrow loops are small holes to fire projectiles through and the filling is rubble. Because of the sturdy structure, it could survive multiple shots from siege weapons and support many humans wearing heavy armour.

Towers
Although towers could be put into the wall category, I have decided not to since many towers stood on their own without being connected to a wall. When I say/type the word "Tower", you probably think of a round tower that reaches into the clouds and has moss and rubbish dangling off it as well as lights covered in vines. The tower would probably be crooked and stupid because Disney and other [naughty word] companies don't do research and instead focus on the looks. Kind of like a lot of minecrafters who build things to look extreme and amazing despite the real thing being pathetic or inelegant. It's fine if you want to fictionalise things but turning a real thing into some rubbish that is completely different is unacceptable unless you say that it's some rubbish that's completely different. Let's move on before I say something bad that causes this to be removed...
Rectangular Towers
Wow! There are rectangular towers? I thought all towers were round and rectangular towers were invented in 2009 when noobs didn't know what circles were!
Yes, child. There are rectangular towers and I despise your ignorance, arrogance and your disregard and disrespect you treat new players by calling them "noobs" as an insult as well as your incapability to do research rather than make up facts or follow some other person's myth about the medieval era because you're too [This has being removed].
Now that I've got that off my chest, rectangular towers were the best economic choice for a tower. They were easy to construct, had a lot of interior space. However they had 1 weak point, or should I say four? The corners of a rectangular tower were the weakest part. If a miner dug under the corner, it would most likely cause the majority of the tower to collapse. Not only does this happen for towers but it can also happen for any wall. The defenders had 2 solutions; create a moat/ditch close to the tower or create a round tower. Let's clear something up quickly; a moat does not always have water in it. Despite this, the Arabian military achitects used them quite often.
Round Towers
Round towers can have two names depending on where they are but because this is "Round Towers" and not the other one, which shall not be mentioned until it comes up, I will be talking about round towers. Round towers were much more resilient to sapping (mining the foundations) and projectiles. However construction and maintenance is more expensive and the inside is smaller. A 10mx10m rectangular tower would have more space inside than a 10mx10m round tower. This is because the corners are being rounded. That is a terrible description but I'm afraid you'll have to deal with it.
Horseshoe Towers
These towers were possibly the best towers available at the time. They had a round wall facing the attackers which made it stronger against incoming projectiles and sapping and a flat wall facing away from the attackers which created more interior space and a bigger area on top of the tower.
Turrets
Castle turrets are completely different to modern turrets. They were not guns. A castle turret is a small tower that rises above and rests on a main tower. You may see things like this on fantasy builds where a smaller tower comes out of the main tower supported by a large triangle-like shape with lots of fences in that triangle. This is not exactly a turret. A turret is normally very close to the wall/tower it's being supported by, most likely to make things cheaper and stronger. What's the point in having a massive thing coming out if a single projectile from a catapult or trebuchet can cause the whole thing to collapse and possibly rip a massive hole in the supporting structure which allows the attackers to charge or shoot through? Turrets were most likely used as a look-out point. Here's a nice one from Alicante Castle in Spain:

Isn't that fabulous?


To be Continued