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It's time for us to strike back against the Institute.— The Sole Survivor

Defend the Castle is a Minutemen main quest in Fallout 4.

Quick walkthrough

Minutemen main quest: Defend the Castle
Go to the Castle
Defeat the attackers.
Talk to Preston Garvey
Reward: 300+ XP
Leads to: The Nuclear Option (Minutemen)

Detailed walkthrough

This quest consists of several waves of attackers that spawn and attempt to take over the Castle. Before the first wave, the Sole Survivor is instructed to create defenses to protect the Castle. However, if the player lacks materials, it is not necessary to raise the defense percentage to 100%, as fast traveling somewhere else can instantly proceed the quest.

Afterward, a broadcast from Radio Freedom will ask all Minutemen in the area to assist the Sole Survivor at the Castle. Once this is done, the waves will spawn.

Brotherhood of Steel

Waves consist of one vertibird and its occupants which put together, consists of a total of ten vertibirds and about 30 Brotherhood of Steel soldiers. Most of the soldiers inside the ship have inventories that cannot be accessed.


Waves of synths and coursers will spawn at various locations. Like the Brotherhood, a large magnitude will also be relayed to the Castle, most often at the southern entrance.


Waves of raiders and attack dogs will attack from either the front side or the back.


Waves of Gunners and Assaultrons will attack from either the front side or the back.

Super mutants

Waves of super mutants will spawn with behemoths.


Waves of mirelurks and a mirelurk queen will spawn.

Quest stages

Quest stages
StageStatusDescriptionLog Entry
10 Quest started
15 Quest started by Form Ranks
16 The Prydwen destroyed while Defend the Castle is active.
70 Player character arrives at The Castle
100 Build defensesThe Institute is preparing to attack the Castle to try to crush the Minutemen before we can build up enough strength to strike them. I need to help defend the Castle before it's too late. OR
I've received word that Raiders/Gunners/Super Mutants/Brotherhood of Steel/Institute synths are preparing to attack the Castle. I should help defend it. OR
I've received word that the Castle garrison needs help.
150 Attack begins
200 Attack defeated - Trigger The Nuclear Option if started by Form RanksThe Institute attack on the Castle has been defeated. Now we can think about turning the tables and taking the fight to them. OR
The Brotherhood's counter-attack on the Castle has been defeated. With the Prydwen destroyed, their threat to the Commonwealth is over. OR
We defeated the Raider/Super Mutant attack on the Castle. OR
The Gunners have been driven back. The Castle stands secure. OR
We repulsed the Brotherhood of Steel attack on the Castle. OR
We defeated the attack on the Castle by the renegade Institute synths. OR
We defeated the attack on the Castle.
210 Post battle scene
450 Talk to Preston Garvey if he gave the quest.
500Quest finishedQuest Complete


  • Completing this quest will automatically fail Semper Invicta, Ad Victoriam, Liberty Reprimed, Blind Betrayal, Tactical Thinking and Mass Fusion. However, completing Ad Victoriam while Defend the Castle is active will successfully complete Defend the Castle.
  • This quest can be gained by becoming an enemy of the Institute after giving Institute network information to Sturges. For example, getting caught while trying to complete Underground Undercover or by completing Spoils of War. Other ways are to kill any named personnel in the Institute, such as Father.
  • The radiant variant (with raiders, Gunners, super mutants, or enemy factions) will occur after the main quest is finished. Synths and coursers will not be able to use teleportation after the Institute demolition.
  • Any companions told to stay at the Castle will participate in the battle, save for those who turn hostile due to siding against their factions.
  • The quest can be given by Preston Garvey, Ronnie Shaw, or an unnamed Minuteman at the Castle. They will mention Institute crows and advise checking the defences.
  • Radio Freedom will broadcast tactical updates during the battle, identifying where each attack phase starts from.
  • The extra unnamed Minutemen that Ronnie calls in may be added to the Castle's settlement population if they survive the battle, potentially increasing the population by as much as sixteen or more. They will not become essential, however, and can still be killed after the quest.
  • After the battle is completed, Ronnie gives a victory speech and Radio Freedom broadcasts a final status bulletin.
  • It is not actually possible to lose the battle. A number of the defenders are marked as essential, and none of the attackers are, so the defenders will always win. There is no failure stage for this quest, and no way to fail it.


  • PCPC Many quests involving the Railroad, such as the weathervane, and Randolph quests will automatically fail if not completed beforehand.[verified]
  • PCPC It is a possibility that Ronnie Shaw's proper dialogue will not appear to end the quest; the only options that will appear are trading and merchant dialogue, leaving the quest unbeatable. There is no confirmed fix for this bug. However, it is possible to instantly end the quest by using the setstage console command: SetStage 000bdb04 450[verified]
  • PCPC It is also possible that during the defend an enemy gets stuck, therefore the percentage of the objective won't move, delaying the next wave, because it never resolves. This can be fixed with a setstage console command. Try SetStage 000bdb04 200 to jump the end of Defend the Castle (%) objective.
  • PCPC Xbox OneXbox One Sometimes, enemy waves will not move upon spawning or will move in the wrong direction in an attempt to fight other enemies in the area. If the quest appears to be stuck, try looking for the enemy wave nearby, and then drawing them back to the castle. Synths can also teleport into the player character-made structures. [verified]
  • [Platforms needed] Sometimes there is a bug where enemy waves will not move upon spawning or will move in the wrong direction in an attempt to fight other enemies in the area. If the quest appears to be stuck, try looking for the enemy wave nearby, and then drawing them back to the Castle. Synths can also teleport into the player character-made structures, so make sure they are not hidden in or among any place that may appear inaccessible. If the synths cannot be found, continuing the Brotherhood quests through Ad Victoriam where one must "defend Liberty Prime," synths teleport into the fight, including the synths that would have been attacking the Castle, providing the opportunity to kill them. This will also complete the "defending the Castle" mission if it was started, and not completed prior to the Brotherhood Ad Victoriam quest. [verification needed]
  • PCPC It is possible to glitch the quest during the synth attack in such a way that all guns, energy weapons, and explosives including Minutemen artillery will cease dealing damage. From that point on, other characters and the player character may fire or throw grenades at each other to no effect, and only bashing or other melee attacks will deal damage.[verified]
  • PCPC This quest was meant to also be a repeatable/radiant quest. However, much like with Defend the Artillery quest, looping errors prevented this from occurring. [verified]
    • This seems to have been fixed with official patch 1.3.
Fo4 Minutemen Flag.png
Fo4 Minutemen Flag.png