When I was done waiting for the evening to fall to start a specific quest by sitting on a chair for six hours, I got three messages of settlements being under attack. Since I rarely see any of them being attacked during 'normal' gameplay, I started wondering what determines the frequency of the attacks?

Is it completely random, or does the chance of happening increases when you are not doing anything? Or are there other contributing factors (if so, which?)

Update: I have full defenses on all settlements and currently play on normal difficulty. One of them even has a defense of 90+ (combined water + food: 44) and is surrounded by walls. One important reason for asking this question is that I would like to prevent fast traveling. The three settlements that got attacked are located in the corners of the map, so I had no chance to helping them all without fast traveling (you fail the associated misc. quest when not responding in time). If I can do something to reduce the chances of it happening, this would reduce that problem.

  • I'm pretty sure the amount of resources/settlers vs the amount of defense you have plays a pretty big role. Commented Dec 16, 2015 at 16:34

1 Answer 1


Typically the more resources and fewer defenses you have at a given settlement, the greater chances it has of being attacked. I will post a credible source if/when I find one, but it mostly seems to be claims from players posting on various forums.

However, I believe the game does mention early on that you should try to get your defense equal to (or greater than!) the sum of food + water. (Hopefully, I'm remembering that correctly). And that makes sense that would contribute to the likelihood of attack. I definitely have Tenpines Bluff attacked much more frequently than the others (i.e. Sanctuary) since I refuse to equip it with defenses. Raiders/supermutants seem much less interested in settlements surrounded by turrets/traps/etc.

Additional information from the Fallout wiki:

It is possible for some settlers to be a Synth which may cause an attack on the settlement from The Institute.

As @DCShannon mentions in their comment, difficult is also likely a factor. A larger proportion of players seem to have settlements get attacked on survival mode, even if defense > food + water.

  • You're right on the (Food + Water) = defense suggestion. If you have defenses less than the sum of these resources, the 'Defense' statistic displays in red while in workshop mode, letting you know it needs to be addressed.
    – king14nyr
    Commented Dec 16, 2015 at 17:17
  • Any particular reason you're refusing to equip Tenpines Bluff with defenses? Commented Dec 16, 2015 at 20:34
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    @MichaelMcGriff, I just like to focus on many of the other settlements. It's not great given the land space (or lack of). Lack of natural water to purify doesn't help either. I just don't want to put the time into improving it (yet). Commented Dec 16, 2015 at 20:36
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    I've rarely, if ever, had a settlement with defense over food + water get attacked, but I hear this happens much more often on survival mode, so the difficulty is definitely a factor.
    – DCShannon
    Commented Dec 17, 2015 at 7:27
  • @ヴァイシャリ, what difficulty were you on? Commented Dec 21, 2015 at 14:35

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