Drafting

An unarmed colony is not going to last long out in the wilderness. In order to defend yourself from armed incursion from raiders and mechanoids, and maintain order in your colony when colonists start suffering mental breaks, you're going to need soldiers.

To make a soldier, select a colonist and press the button marked with two crossed swords (image needed). Unlike a colonist, a soldier can be precisely controlled as in deciding where he/she shall stand, what target to fire upon and so on. Soldiers will also use any viable terrain features or structures they're standing next to as cover to protect themselves during a firefight with your enemies.

A soldier carrying a weapon will hold it out and ready at all times, automatically attacking any hostile character or animal that comes within range. If you draft a colonist who does not have a weapon, you will be immediately notified of such -- it is advised to always ensure soldiers are armed, unless you want them to use their bare fists to subdue someone with a minimal chance of killing or crippling them. Note that soldiers equipped with ranged weapons can still attack with their fists if ordered to engage in melee, or if engaged by an attacker in melee combat.

Soldiers can arrest colonists and neutral human characters (such as drifters), dragging them to the nearest convenient bed marked for prisoners. They can also arrest colonists who have suffered a non-violent mental breakdown, which can be very helpful if someone starts binging on alcohol or gives up and tries to leave the colony entirely. To do so, select a soldier and right-click the desired captive, then select "arrest <name>" from the menu.

Orders

A soldier can be directly ordered to move where you want them to, and shoot what you tell them to. To move a soldier, select them, then right-click on any pathable tile on the map. If you band-box select multiple soldiers at once, you can order them all to move to the same area.

A soldier can be combat-trained by having him/her attacking a dumping area, this will increase the chance of hitting a target, be aware that if the training is too long the soldier will have a mental breakdown due to extreme hunger and sleep deprivation, to prevent this switch the soldier back to be a colonist before the mental brake happens by clicking the sword button again.