Castle

The simplest from of castle is the tower keep. Typically three stories, a great hall, apartments for the household, and apartments of the family.

A more complicated castle starts with a tower keep, and builds a curtain wall around it, as a shell. Frequently the castle was constructed on a hill, on an island, at the junction of two rivers, or on a man-made mound. The obstacle, whether elevation, water, or both, made direct approach to the wall difficult. This difficult approach was designed to create an advantage for the defender who already has a height advantage and a cover behind a wall, but also can shoot at someone climbing or crossing a water obstacle. Often an attacker's plan is to build siege weapons, which creates time for aid to come and break the siege. The other plan an attacker might have is to starve defenders, so a well provisioned castle is the norm. Supplied by the production of a manor, a castle should always be well supplied.

A more sophisticated shell keep adds defensive towers along the wall and at the gate, creating a double gate, or gate house. Instead of a simple curtain wall defended by archers, the curtain wall is broken up by towers placed at keep points to create a clear view of the countryside, interlocking fields of fire, strong places for resisting an assault, and distributing supplies along the wall. With this additional expense, the curtain wall is also probabaly thicker and taller than a simple shell keep.

Making a castle bigger requires more defenders and more supplies. Instead of doing this, the next development of castles makes them deeper. A concentric castle is castle within a castle. If the outside curtain wall was penetrated, the defenders could fall back to an inner wall. This allows a given number of men to defend a place much longer than in an advanced shell keep. A castle is essentially a way to allow one man to fight many at once, by making the castle deeper, it was no longer possible to breech the castle and equalize the odds. The concentric castle simple reset the defenders to an inner defense and started the process all over again.

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No matter what castle is employed, its defensibility can be greatly enhanced by terrain. Cliffs, lakes, and other impassable terrain can block armies if not adventurers. Combined with hills, rivers, moats, walls, towers, and other obstacles, some positions could make a castle almost impregnable by making the ratio of attackers to defenders so high that the benefit of taking the castle would not justify the cost of its capture.