Fallout 4 Battle of Bunker Hill Guide

Fallout 4 Battle of Bunker Hill Guide

For me, the Battle of Bunker Hill is one of Fallout 4‘s most memorable quests. In the grand scheme of things, it’s totally unimportant to the point that the Railroad and Brotherhood don’t really care about how you resolve it. Yet, it’s a massive, full-scale firefight between three factions with you stuck in the middle of the storm.

Despite being able to tell both the Railroad and BoS about the plan at Bunker Hill, you need to follow the Institute quest to complete it. However, despite being forced into the Institute’s side of the quest, you can resolve it in favor of any of the three main factions, although the outcome doesn’t matter too much.

The entire quest is more complicated than it needs to be, hence why I’ve put together this Fallout 4 Battle of Bunker Hill guide. I’ve laid out all your options as plainly as I could, so hopefully, you can resolve the quest in a way that suits your character and playthrough.

Quest Details Up Front

  • Quest Location: Bunker Hill.
  • Quest Giver: Father.
  • Requirements: Complete Synth Retention, have access to the Institute.
  • Length of Quest: Short.
  • Difficulty: Very easy/Very hard, depending on faction relationships.
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Quest Synopsis

Father learns of a group of runaway Synths being held in Bunker Hill. The group is under the protection of the Railroad, making their retrieval a difficult task. He entrusts the Sole Survivor, along with Courser designation X4-18, to lead a military operation into Bunker Hill and return the lost Synths home.

Brief Walkthrough

Speak With Father

Speaking with Father back in the Institute will reveal that a group of runaway Synths has been located in Bunker Hill. The Synths are under Railroad protection, meaning retrieving them isn’t as simple as walking in and grabbing them.

He will entrust you with assaulting Bunker Hill and bringing them home, with the assistance of Courser X4-18.

Meet With the Courser

After speaking with Father, you need to meet up with Courser X4-18. However, before that, you can choose to inform either, or both, the Railroad and Brotherhood of Steel about the operation.

Both groups will be at Bunker Hill regardless, but Maxson and Desdemona will inform you of what they would like you to do with the Synths once you find them.

Leave the Institute and make your way over to Bunker Hill. Courser X4-18 will be there waiting for you.

Deal With the Synths

The front gate to Bunker Hill will be locked, forcing you to go around the settlement to get inside. Both the Railroad and Brotherhood will be there, turning the area into one massive free for all. However, if you’re allied with both groups while doing this quest, they will not be hostile to you. This makes Battle of Bunker Hill one of the easiest quests in the game, as you can just walk through the combat without being attacked.

Walk, or fight, your way into Bunker Hill and take the hatch leading to the utility basement. Inside the basement, you’ll find the group of Synths.

Here, you have three choices:

A. Retrieve the Synths for the Insitute and allow the Courser to take them back. This is the Institute’s preferred resolution.

B. Kill the Courser and free the Synths. This is the Railroad’s preferred resolution.

C. Kill the Synths to send a message to the Institute. This is the Brotherhood of Steel’s preferred resolution.

Regardless of how you deal with the Synths, return to the C.I.T. ruins and speak with Father. If the Synths were released or killed, you will need to be careful with your dialogue choices to avoid being banished from the Institute here.

Extended Walkthrough

Speak With Father

After you complete Synth Retention, Father will want to speak to you regarding an ongoing situation in Bunker Hill. According to his intel, the Railroad is using the settlement to hide a group of runaway Synths. Naturally, those Synths need to be brought back to the Institute.

Rather than leaving the Synth Retention Bureau in charge of this operation, though, he wants you to handle it. He’ll explain that you’ll have backup in the form of a Courser designated X4-18 before sending you off on your merry way.

Leave the Institute, but rather than heading straight off to Bunker Hill, you might want to make a few stops.

Unlike Mass Fusion, there is no alternative version of this quest for the different factions. However, it is possible to resolve it in favor of them. So, depending on your allegiances, you might want to pop into Maxson and the Brotherhood, as well as Desdemona and the Railroad.

Despite both leaders assuring you that the intel you’re bringing on the Institute’s operation at Bunker Hill is the first they’re hearing of it, each faction will be at the battle regardless. You also don’t need to speak with them to resolve the quest in each one’s favor, so this is more of a formality if anything.

The Brotherhood will want you to kill the Synths to send a message to the Institute. This means you’ll have to kill the Courser, too.

The Railroad, on the other hand, wants you to free them despite the Synths being in the group’s protection already. Again, this forces you to kill Courser X4-18.

Speak with the factions, or don’t, then head over to Bunker Hill to meet with Courser X4-18.

Meet up With Courser X4-18

Keep in mind that Bunker Hill will remain in its default state until you speak to Courser X4-18. So, if you need to do anything there immediately, take care of it before you speak to him.

Once you meet up with the Courser, Bunker Hill’s status will change and each of the factions will arrive there in force regardless of whether or not you informed them of the operation.

When you arrive at Bunker Hill, the front gate is going to be locked. You’ll need to enter the settlement through an open door on its East flank, so that’s the direction you need to be fighting towards.

Faction Relationships

The Battle of Bunker Hill can either be Fallout 4’s easiest quest, or one of its hardest.

The only characters present at the battle are Railroad, Institute, and Brotherhood combatants. However, at this point in the game, you’re able to be both friendly with, and a member of all three factions. In other words, if your standings with each one is good, nobody will be shooting at you.

Despite X4-18 being hostile to both BoS and Railroad forces, they won’t be hostile to you in turn, only to him. In other words, it’s possible that you’ll be able to completely walk through this quest without ever having to fire a bullet.

On top of all this, Courser X4-18 is considered an essential NPC until you make him hostile to you. He’s also the only essential NPC in the entire fight. So, if you’re patient enough, you can let him kill everything in sight, netting you a stupidly large amount of free loot.

Deal With the Synths

If either, or both, the Railroad and Brotherhood are hostile to you, you’ll need to fight through them and into Bunker Hill itself. Note that killing Courser X4-18 will turn the Railroad soldiers there friendly immediately.

Inside Bunker Hill itself, behind a counter by the marketplace, you’ll find a small hatch that leads down into a utility basement. Head inside and follow the room layout until you reach the room with the Synths.

There are four Synths in the group, Z3-22, B2-57, Y9-15, and F6-33. One of them will offer you 60 caps as a bribe. You can accept the caps with no consequences before dealing with the Synths however you see fit.

There are three possible resolutions to the Battle of Bunker Hill.

Institute Resolution

The Institute resolution involves returning the Synths to the Institute like Father requested.

To do this, make sure you haven’t killed Courser X4-18 up to this point. Speak with each of the Synths and activate their recall codes. X4-18 will then return the group of them to the Institute.

Doing this will have no consequences with any faction other than the Insitute, which approves of it. Both the Brotherhood and Railroad will remain friendly or hostile depending on their current states, and your reputation with each will not change.

Brotherhood Resolution

The Brotherhood Resolution to the quest involves executing the group of runaway Synths. You don’t have to say anything to them or do anything fancy, just put a bullet in each of them.

Doing this will turn the Courser hostile, though, forcing you to kill him.

Railroad Resolution

Lastly, you can Kill Courser X4-18 and free the Synths for the Railroad. Doing this, like with the Institute resolution, will not affect your standings with any faction other than the Institute itself.

Before, or after, you kill X4-18, simply speak to the Synths and tell them they’re free to go. If the Courser is still alive, this dialogue will turn him hostile.

Return to Father

When you finish up with the Synths, you’ll need to head back towards the Institute and speak with Father. Rather than being underground, he’ll be on the roof of the C.I.T. ruins. You’ll be able to access the roof through a staircase inside the main entrance of the ruins.

When you reach Father, the conversation you have will differ depending on whether or not the operation at Bunker Hill was a success.

If you returned the Synths to the Institute, he will shower you in praise and reward you with 500 caps before triggering the next quest in the Institute’s main questline.

However, if the Synths were killed or freed, you will be at risk of being banished from the Institute, locking you out of the faction for the rest of this playthrough.

Father will demand to know what went wrong during the operation. If you tell him the truth and admit that it was your fault, you will be kicked out of the Insitute. Instead, tell him that it doesn’t matter, or that you were ambushed. Both of these responses will preserve your ability to continue with the Institute’s main questline.

The Battle of Bunker Hill will finish following this conversation. If your access to the Institute is preserved following this, Mankind – Redefined will trigger.

Quest Rewards

There are a handful of rewards that come about from you finishing the Battle of Bunker Hill. First, you’ll get a chunk of XP. This is standard regardless of what way you decide to resolve the quest.

Second, if you return the Synths to the Institute, Father will reward you with 500 caps.

Lastly, and most importantly, it opens up your ability to recruit Bunker Hill as a settlement.

Head back there after the battle and speak with Kessler. You can mention that you’re able to protect the settlement from future attacks, unlocking its workbench for you to use as you see fit.

This isn’t the only way to unlock Bunker Hill as a settlement, but it is the fastest and easiest.


Question: How do you beat the Battle of Bunker Hill for the Railroad?

Answer: Unlike Mass Fusion, there is no alternate version of Battle of Bunker Hill. You will have to play through the quest with the Institute up until its resolution. If you want to complete the Battle of Bunker Hill for the Railroad, kill the Courser and free the Synths.

Question: Should I kill the Synths at Bunker Hill?

Answer: Killing the Synths at Bunker Hill will force you to kill the Courser and put your relationship with the Institute in jeopardy. However, it is the Brotherhood’s preferred outcome.

Question: How do I complete the Battle of Bunker Hill with the Brotherhood?

Answer: To complete the Battle of Bunker Hill with the Brotherhood of Steel, you need to kill both Courser X4-18 and the group of runaway Synths.


That’s it for this Fallout 4 Battle of Bunker Hill guide. It’s a pretty short quest that’s more about proving yourself to Father than it is actually bringing the Synths back. It’s like a stepping stone into the Institute’s main questline, rather than being an important quest itself.

However, despite that, it’s an awesome set-piece. Big battles in Fallout are iconic. Just remember the first time Liberty Prime booted up in Fallout 3. While Battle of Bunker Hill isn’t at that level, the roaring Vertibirds and trio of battling factions turn the game into something more akin to an action-shooter than a post-apocalyptic RPG, at least for a few minutes. That might not be for everybody, but it certainly scratches an itch of mine.

The only issue you should come across with the quest is how to resolve it in favor of the different factions, although you really don’t have to for any reason beyond role-playing purposes. Still, I hope this Battle of Bunker Hill guide spelled your options out as understandably as possible.

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