The Battle of Bunker Hill

The Battle of Bunker Hill is an Institute main quest .
==Quick walkthrough==
==Detailed walkthrough==
Father orders the Sole Survivor to go to Bunker Hill to reclaim some escaped synths held there under the protection of the Railroad. The player will have backup from a courser designated X4-18. Exit the Institute and proceed to Bunker Hill.
Optional: If Shadow of Steel has been completed, the player can warn Elder Maxson about the Institute's plans, and he will ask the player character to kill the synths when the opportunity arises. If Tradecraft has been completed, it is also possible to warn Desdemona that the Institute is on its way, which will allow the Railroad to anticipate their arrival and lay an ambush. Both groups can be warned or ignored, though all three factions will be present at the hill battling regardless, despite Desdemona and Maxson saying they would have had no idea of the Institute's intentions if the player had not informed them.
At Bunker Hill, the battle begins only after the player meets with X4-18. He explains the situation to the player and calls in backup, at which point the player can pass a hard persuasion check to get more synth relay grenades. (Note: If both the Brotherhood and Railroad were informed, this second piece of dialogue will be unavailable and the courser advances towards Bunker Hill after the first dialogue.)
The main doorway into the settlement is locked, requiring the Sole Survivor to walk around to the east (right) side of the settlement where an opened door can be found. Alternatively, it is possible to climb the trailers to the right of the locked gate and jump over the fence. The inhabitants of Bunker Hill will cower during this firefight, so it is likely that most if not all of them will remain alive (due to varying "essential" statuses), despite the free-for-all taking place around them.
Once inside Bunker Hill, there will be a small hatch leading to a utility basement behind the first counter on the left, nearest the actual monument. After following the catwalks to a room far in the back, the player finds the runaway synths Z3-22, B2-57, Y9-15 and F6-33. Here the player has three options:
# Option 1: Escort the courser to the escaped synths and let him take them back to the Institute. To complete this option, proceed through the fighting to where the synths are hiding, activate their recall codes by speaking to them individually and allow X4-18 to take them back. This action will not turn the Railroad or the Brotherhood hostile (provided they are not hostile already) and will not damage the player's good standing with either faction.
# Option 2: Kill the courser and free the synths. In dialogue with the synths, tell them that they are free to go, which immediately turns the courser hostile and brings up the objective "kill the Courser." If not allied with the Railroad, killing X4-18 will immediately turn the Railroad members and turrets friendly (which will be revoked if one opens fire on them. If X4-18 is killed above ground, Railroad members underground may still be hostile).
# Option 3: Kill the escaped synths. Killing them makes the courser hostile, but killing him immediately switches the Railroad members to friendly, whether the synths are killed before or after.
* Additionally, the player can accept an offering of 60 caps from one of the synths. This does not affect the available choice, so it is possible to accept their money and still kill them or send them back to the Institute anyway.
Regardless of choice, a new objective will be added to report to Father on the roof of the C.I.T. ruins. The roof is accessible from the easternmost staircase inside the main entrance of the ruins. After a short discussion about how the Commonwealth has declined, Father speaks of Bunker Hill:
#If Option 1 was taken, he applauds the player character's success and rewards them with 500 caps.
#If Option 2 or 3 were taken, he demands to know what happened. Wrong dialogue choices here, such as admitting it was the player's fault, can lead to being banished from the Institute. Stating that it does not matter, or that they were ambushed, makes Father upset with the outcome but ultimately preserves the player's good standing with the Institute.
The quest concludes, and if the player's good standing with the Institute is preserved, Mankind - Redefined begins.
==Quest stages==
==Notes==
* Until speaking to X4-18, Bunker Hill remains in its default, non-combat state. This allows the player to pursue other quests, such as Traffic Jam and Prep School, and they will become available again once this quest is turned in. Once X4-18 is spoken to, however, Bunker Hill's combat state will be loaded, with Railroad heavies instantly in position, the front gate locked ("Requires key") and Vertibirds flying in from the background.
* When meeting up with X4-18, Vertibirds will be heard in the background. Hurrying through the dialogue will allow the Sole Survivor to persuade him through a hard Charisma check for three synth relay grenades. Taking too long will skip that part of the dialogue and instead receive the recall codes.
* If Tradecraft has not been completed, the optional objective to inform the Railroad will not be available. Similarly, if Shadow of Steel has not been completed, the option to inform the Brotherhood of Steel will not become available. If these quests are completed once "The Battle of Bunker Hill" has been added to the journal, the optional objectives to inform the factions will not be added.
* If the player is an inducted member of the Railroad and the Brotherhood of Steel (i.e. completing Tradecraft for the Railroad, Call to Arms for the BoS) and in good standing, the fighters of all three factions will be marked as friendly, ignoring the Sole Survivor. This not only mitigates most of the danger this mission might pose, it also allows for the acquisition of ludicrous amounts of valuable loot.
* If Underground Undercover and From Within have not been added to the journal (possible by entering the Institute with the help of the Minutemen), the player must go through those dialogues before Desdemona and Maxson can be warned.
* If the player character "chooses a side" by firing on the other factions' NPCs, the chosen side will slowly gain the upper hand until they've successfully dispatched the rest of the factions' reinforcements. If the player has remained "neutral," X4-18 will eventually kill everyone else because he is marked as "protected" and cannot be killed unless attacked by the player. If the player character fires on one side, hostile members of that faction will have to be fought on the way back out. The synth striders brought to the battle do not turn hostile if the courser is killed.
** Informing any other factions ahead of time is not required to employ options 2 or 3 (aside from possibly bugging the "Deal with the synths" objective as displayed in the journal); one can kill the courser or the synths as one sees fit. It is also possible to accept a bribe of 60 caps from the synths, no matter what option one chooses in dialogue. 
* Upon completing this quest, the player can unlock Bunker Hill as a settlement by speaking to Kessler. She cites the player's "powerful friends" and allows them to have the run of the place.
** Completing this quest is not the only way to unlock Bunker Hill as a settlement. Should the Sole Survivor get Banished from the Institute before completing this quest, one could complete Prep School and then talk to Kessler afterwards.
* Companions have unique thoughts after the battle.
* Danse and Deacon have no reactions to warning either the Brotherhood or the Railroad. Similarly, their affinity does not change in response to killing the synths, freeing them, accepting a bribe or sending them back to the Institute.
==Behind the scenes==
The title of this quest is a reference to the historical Battle of Bunker Hill, a conflict taking place during the American Revolutionary War.
==Bugs==
Category:Institute quests
Category:Fallout 4 quests
pl:Bitwa o Bunker Hill
es:La batalla de Bunker Hill
pt:A Batalha de Bunker Hill
ru:Битва за Банкер-Хилл
uk:Битва за Банкер-Гілл
zh:碉堡山戰役