Protection

Protecting one's settlement is a complex affair. The primary goal is ensure that they can defend themselves. The secondary goal is maximizing the defense stat, to minimize one's settlers' exposure to enemies. To be on the safe side:


 * 1) Build defensive structures to increase the defense rating. Note that turrets are autonomous, but larger ones require power to function. Guard posts don not require power, though they do require a settler to be assigned to them in order to generate defense.
 * 2) * Placing turrets and guard posts with snipers in elevated positions will make it harder for melee enemies to get to them and provide clearer lines of fire. It can also help against grenades.
 * 3) Companions who are not accompanying the player character will assist the settlement they are at if it gets attacked. Assign companions to settlements accordingly.
 * 4) Players with the Automatron add-on can build robots to help defend settlements. They can be left to roam or assigned to a guard post the same way as a settler. Note that automatrons are not essential, and can be destroyed.
 * 5) The game generates attacks on settlements in two ways:
 * 6) * It generates Defend Settlement missions for one of the player character's settlements.
 * 7) * There is a chance for an enemy attack to spawn anytime upon visiting a settlement.
 * 8) Having a defense rating equal to or greater than the sum of a settlement's food and water will prevent attacks from enemies entirely, according to the game's settlement tutorial.

Notes:
 * If the player character builds a siren near a guard post, the guard will activate the siren upon spotting an enemy. The siren will alert settlers in the area that enemies are approaching, and they will move towards the siren to help defend. Wandering settlers can also activate a siren, but there's no way to be sure anyone will be there.
 * Multiple sirens can be daisy-chained to alert larger areas, but testing is needed to determine whether distant settlers move towards the enemy or just towards the nearest siren.

Equipping settlers
It is ideal to equip settlers with whatever surplus guns available. Newly recruited settlers start with a pipe gun, or rarely, a double-barrel shotgun.
 * With the exception of the Fat Man and missile launcher, settlers do need some ammo for their guns. Unlike companions, settlers do not use up their ammo; they just need some in their inventory. Testing indicates that as long as they have at least one unit of ammo in their inventory, they ignore its consumption entirely.
 * The enemies a settlement will face is based on the level range of the cell the settlement is located in on the map. In general, settlements located further south will face tougher enemies.
 * The level the player character is at when first visiting the cell a settlement is located in (it does not need to be the settlement itself) may also play a role in determining the level range of the enemies.
 * When looking at weapon damage, keep in mind that settlers do not have perks.

Weapon mods

 * 1) Extensive testing indicates that settlers always use hip-fire, regardless of whether the animation shows them looking down the sights or not.
 * 2) Testing indicates that settlers are either unaffected, or else barely affected, by recoil.
 * 3) Reportedly, when using scopes, settlers only use the accuracy stat. The zoom has no effect on them. Therefore one of the long scopes provides them with the most accuracy at all ranges, not just at long range as it would be with the player character.
 * 4) Settlers with recon scopes will add target indicators to the player character's compass, just like when they themselves uses them.

As a result, the best mods for settlers are quite different from what a player character might choose. In general:
 * Light barrels work the best, due to points 1 and 2 above.
 * Short light barrels have the very best hip-fire accuracy, and seem to be the best choice for automatic weapons. Also a good option for semi-auto pipe pistols.
 * Long light barrels seem to be the best choice for bolt-action and semi-auto rifles.
 * For laser/plasma weapons, an improved short barrel with a fine-tuned beam focuser provides the most accuracy. A sharpshooter's grip, when available, will provide a small additional boost. A sniper barrel provides higher damage and longer range in exchange for lower accuracy. Automatics are also very effective, and the barrel choice is obvious there.
 * An automatic beam splitter can be very effective at shorter ranges since settlers do not experience the effects of recoil. They also tend to fire at ranges that render the weapon ineffective due to the scatter.
 * Long scopes are the best choice for all weapons, regardless of the range used.