Take it Back!

 is a Fallout 3 quest. It is also an Xbox 360/PC achievement and a PlayStation 3 Trophy.

Attack!
When you reach The Citadel, Owyn Lyons and his daughter will be preparing for an assault on the purifier. After informing them of the situation, Sarah's squad is mobilized and Scribe Rothchild, after some initial reluctance, will activate Liberty Prime.

Prime is launched in a rather stereotypical way for super weapons as seen in movies and TV shows, in which the lead researcher (Scribe Rothchild, in this case) demands it not be used and shouts things similar to, "Testing hasn't been finished yet!" or, "It's only the prototype! Are you mad!?!?" Despite his warnings, Prime is launched and used without any malfunctions.

To begin the advance on the Jefferson Memorial, the player must speak with Sarah Lyons. Note that once the order to attack has been given the green light, all functions and services in the Citadel will cease. All NPCs will spout encouraging phrases such as, "The purifier is as good as ours!" if spoken to. If the player has anything to do in the Citadel, he or she must complete their task before commencing the attack.

Following the order to attack, Liberty Prime will be hoisted out of the Citadel on a crane and the Lyons' Pride will follow it, as should the player. Prime actually crashes his leg on the wall in the Bailey on the crane, however it does not heavily damage him. Once outside the Citadel, Prime will begin stomping his way to the fallen bridge, killing everything in its path. Liberty Prime will take down the photonic resonance barriers set up by the Enclave by walking into them.

Once on the bridge, the Enclave will desperately throw everything it has at the Brotherhood's machine: soldiers, Vertibirds, and artillery. Their efforts are entirely for naught, and Liberty Prime will decimate everything thrown at it. Liberty Prime may or may not miss a few of the troops in the confusion. Liberty Prime will destroy any incoming Vertibirds, so the player only needs to worry about ground troops. Targeting the ground troops can be a pain due to all the screen-shaking occurring (Mini-Nuke and artillery shell explosions) so V.A.T.S. is a good alternative to freehand aiming. The Lyons' Pride soldiers will also do a fair job of mopping them up. The artillery shells tend to arc in from both sides of the bridge, but are notoriously inaccurate. Exploding vehicles are very deadly, so the player should find cover either behind Liberty Prime, or behind previously exploded vehicles. The player may feel intimidated by the concussive blasts, but will rarely take damage from them.

Liberty Prime cannot be stopped, and will inexorably clear a bloody path to the Memorial. The player and Lyons' Pride can come under attack from targets on a catwalk between buildings after clearing the bridge from the Citadel. It is possible to hustle to the near building, enter the door, run up several flights of stairs, and emerge beside the enemies on the catwalk, but this is a very impractical way of doing the job: a ranged weapon will work just fine. Melee and Unarmed characters can simply let the Lyons' Pride finish up these troops, but they take quite a while. Either way, Liberty Prime will continue carving his way though the resistance, past the Irradiated Metro and onwards to a second bridge. At the end is where Liberty Prime stops, and holds his position along with the rest of the Lyons' Pride while Sarah Lyons and the player dash inside the Jefferson Memorial through the Gift Shop. Note that, if you hesitate, a significant force of Enclave soldiers will be deployed nearby, either from the bridge or the catwalks around the memorial. Liberty Prime will destroy them.

There is light resistance inside the Gift Shop, usually three or four Enclave soldiers. The player as well as Lyons should be able to clear the room. Grenades work well in these quarters.

The Rotunda
After entering the Rotunda, the doors seal shut. Not locked, nor pickable, completely sealed. There is no leaving the Rotunda after entering it. Colonel Autumn is waiting for the player and Lyons in the Rotunda, and locks the player in dialogue. He seems unsurprised at the player's arrival at the purifier. The player has two choices at this point:


 * Talk Colonel Autumn out of attacking. This is a rather difficult speech check, even with 100 Speech (around a 50/50 chance assuming 5 Charisma). After conceding defeat, he will leave the player to their fate. After this, Sarah Lyons will give a short remark on the player's decision, depending on his or her Karma. (NOTE: If you were able to convince Eden to blow up the Enclave base in the last quest, you will have the option to use that as an easy speech check.)
 * Fight Colonel Autumn. The Colonel isn't terribly hard to defeat, but his bodyguards are tougher. It is possible to attack the Colonel and kill him before the dialog begins.

After resolving the situation and heading up the stairs to the control room, a panicked Dr. Li will key the intercom: Project Purity has sustained severe damage, and will soon self-destruct!

Final choices

 * NOTE: Those with Broken Steel installed have additional options in completing this quest, as detailed in the second decision option.

Now, the game has the player make one final decision: who will activate the purifier. The radiation levels are fatal once the purifier is activated, so whoever goes in isn't coming out (Rad Away, Rad-X, and Radiation Resistance do not matter, as it is a cut-scene).

Decision 1: Sacrifice yourself or Lyons
The obvious choice is that either the player or Sarah Lyons must sacrifice their life to get the purifier going and prevent the destruction of Project Purity. If the player hasn't figured it out from James' notes and recordings, the purifier password is 2-1-6 (referring to the verse from Revelation which Catherine loved). If the player follows James to the purifier when he first enters the Memorial in The Waters of Life, James points out the code and repeats the passage. The player is supposed to infer it from James' dialogue about the Lone Wanderer's mother, and the picture hiding his safe in the Vault 101 clinic. If the player chooses to convince Sarah to do the job, the Lone Wanderer will tell her the code in dialog. If the player has the Broken Steel add-on, the player's karma will be raised by 1000 if they decide to activate the purifier themselves. No karma is gained if the player sends in Sentinel Lyons or one of their companions.

Contaminating the water
If you choose to activate the purifier yourself, this is the time to insert the Modified FEV created by President Eden into the water filter, assuming you want to and didn't give it to Elder Lyons. As in Fallout 2, the only creatures spared by the Modified FEV are pure strain humans who are still within vaults or the Enclave and possibly the Brotherhood of Steel. This would reverse a great deal of genetic damage done by the nuclear apocalypse, but at the cost of complete eradication of nearly all life on the wasteland. This decision is actually listed in the player's Pip-Boy 3000 as a separate quest called Project Impurity; however, it cannot be completed if the player turned in the Modified FEV to Owyn Lyons before departing the Citadel.

Inserting the Modified FEV lowers Karma by 1000. Inserting the Modified FEV has a long-term game impact if you have downloaded Broken Steel. The Aqua Pura thus created by purifying the water is now infected by the virus, and as your character is not a pure-strain human as Eden believed, it will cause a negative effect on your SPECIAL stats and kill you if three or more are consumed in quick succession. A warning will come up that reads Continued consumption of FEV-laced water will be fatal to remind you of this fact.

Decision 2: Have your radiation-resistant companion do it
Without Broken Steel installed, your companions will refuse to do the job. Naturally, of the seven, four would die just as easily as you, and they aren't willing to do it. Even Fawkes, Sergeant RL-3, and Charon who are highly resistant or outright immune to radiation, will simply decline. With Broken Steel, however, the latter three will now agree to do the job, as they can do it safely.

Companion Responses
Fawkes, one of the companions the player may take with them, has great radiation resistance (or possibly immunity) as a result of being a super-mutant. However, like any other companion character, his dialog option has him refuse to enter the chamber, mysteriously claiming it is the player character's "destiny."
 * Fawkes

Whether this is because Fawkes believed himself unable to survive, if he had other reasons for declining the player (such as feeling that the debt had been repaid, or if he genuinely believes in destiny) is not explained. Regardless, Fawkes turns out to be a red herring: the player is forced into a decision to either sacrifice themselves or make a true hero (Sentinel Lyons) make the sacrifice for them. Amusingly, Fawkes may nonetheless follow the player into the chamber if his following distance is set to "close".

If the Broken Steel add-on is installed before beginning Take it Back!, Fawkes will agree to enter the chamber, stating: "Ah, of course! My immunity to radiation makes me a far better candidate for surviving in there." Fawkes will be briefly staggered when the purifier activates, but does not collapse like the player or Sarah Lyons would. The end will show him as "A True Hero" instead of Lyons.

As intelligent as the canine may be, there is no option to have Dogmeat activate Project Purity. Instead, a new dialog option opens up, wherein the Lone Wanderer can say some final words to his or her canine companion, stating: "I think it's time for us to say goodbye, old buddy. Take care of yourself, okay?" Dogmeat whines in response.
 * Dogmeat

Even if you took Sergeant RL-3 (a Mister Gutsy combat droid, which is immune to radiation) into the rotunda with you and command it to go in to turn on the purifier he declines and says:
 * Sergeant RL-3

There is no Robotics Expert dialogue option in the conversation.

Like Fawkes and Charon, if Broken Steel is installed before starting Take it Back!, RL-3 can be ordered to go into the control chamber and activate the purifier. He will state that his "superior design and programming" will be able to withstand the hostile environment, followed by an exclamation that "This will mean a battlefield commendation for sure." After starting the purifier, he apparently cringes from the radiation spike, but is otherwise unharmed. The ending will show him as "A True Hero" instead of Lyons.

Charon will not activate the purifier for you. The dialog is as follows:
 * Charon

Just like Fawkes, if Broken Steel has been installed before this quest, Charon can be told to enter the control chamber and turn it on. The player will remind Charon that he must obey whoever holds his contract, then order him to enter the control chamber, to which Charon grudgingly agrees. Unlike with Fawkes, no mention is made of the fact that Charon, being a Ghoul, should be unaffected by the radiation in the chamber. If Charon is used to start the purifier, he will replace Sarah Lyons as "A True Hero" in the ending movie.

Butch, understandably, will refuse out of fear of dying and of becoming a ghoul, stating:
 * Butch

She respectfully refuses, of course:
 * Star Paladin Cross


 * Clover

Apparently, there are limits to Clover's mental conditioning and slave collar. She refuses as well:


 * Jericho

Jericho also refuses, stating simply:

Decision 3: Do nothing.
If the player chooses to, they may simply not go into the purifier. This results in Project Purity quickly exploding, along with any chance of pure water for the entire wasteland or to introduce the Modified FEV into the water supply. An ending sequence will still be played, and it will count as an ending (obviously completing the quest and unlocking the "Take it Back!" achievement/trophy). The last thing the player will see is the destruction of the purifier. Just like all other endings, this does not result in free-play. Even if the player has Broken Steel installed this option ends the game. With no purifier the events of Broken Steel could not happen.

Game over
Without the Broken Steel add-on, the regular ending will be shown and game ends here. However, if Broken Steel has been installed and assuming the player activates the purifier instead of allowing it explode, the player will wake up two weeks later at the Citadel.

As you wake up, you encounter Elder Lyons, who explains that you and Sarah Lyons were both knocked unconscious due to an energy spike in the purifier and were found and brought back to the Citadel. Sarah has not yet recovered from her coma. (Note: If you make Sarah start the purifier she will be dead at this point.) Elder Lyons also explains the consequences of your actions, including the destruction of Raven Rock or the insertion of the Modified FEV into the purifier. The first Broken Steel quest, Death From Above, starts here.

Bugs

 * If a player causes the opening cut scene to start but leaves, (i.e. by leaving once their conversation is started, but before the player is immobilized) there is a chance that when the player returns to allow the cutscene to play out, none of the controls will work and the game will act as if Elder Lyons and Sarah are speaking, therefore barring the player from starting Take It Back! or beginning the Broken Steel expansion.
 * When Liberty Prime is crossing the Potomac bridge, depending on the bombardment, it is possible for Liberty Prime to get stuck on the bridge after being hit by a blast. Liberty Prime may also get stuck by the Enclave's drop ships on the bridge. Firing a few Mini Nukes with the Fat Man on the drop ships will clear the road and Liberty Prime resumes its path.
 * At one point, all members of the Lyons Pride kept shooting at an Enclave corpse (as did Charon) and the player was unable to interact with the body. Charon will simply stop and follow the player once again if the player walks too far away, but there is no known way to get the Lyons Pride to continue.
 * When Liberty Prime is about to cross the first bridge and lead the attack, during the initial bombings, the Brotherhood soldiers may simply turn back around and stand down before even crossing the bridge, while Sara Lyons will be the only one following you and Prime.
 * After leaving the Citadel, Liberty Prime may just stop moving altogether. If this happens, reload an earlier save and he should start to move.
 * It's possible for the game to randomly freeze during initial invasion, it could be caused by moving too far away from the Pride.
 * It is possible for Sentinel Lyons to not follow you into the Rotunda, leaving you with no way to enter the purifier and no way to leave the Rotunda. If this still isn't fixed after restarting Fallout 3, use the console command player.placeatme 0001D430 . This MIGHT solve the problem, or it might not. Can also be solved by quick-saving on the PC in the Rotunda and then quick-loading.
 * Liberty Prime may stand in place and not commence his attack. It is possible the Lyon's Pride cannot be assembled if Paladin Vargas was killed earlier in the game. If so, his body will be in front of the Citadel entrance; you will need to carry him over to Prime's feet to get him to initiate his attack. Or if you can't find the body then use the console Command player.placeatme 0001d44e.
 * If you are well-rested right before beginning this mission, (and have purchased Broken Steel DLC) you will retain the well-rested XP bonus through the "two weeks later" break into the mission completion.
 * If you download the Broken Steel expansion, Sarah Lyons may sometimes ask to make sure the room is clear after she talks to the Doctor, despite no enemies being in the room. This will make it impossible for the player to activate Project Purity. This glitch can be fixed if one downloads the V1.5 update/patch. Also you can make a save when Sarah closes the chamber door (possible if you haven't yet installed broken steel, if you have then delete it from the hard drive). Now after you have saved the game you install broken steel.
 * Similar to the above, Sarah Lyons might ask to clear the room but instead face the intercom and repeat "Steel be with you" over and over. when pushed away from the intercom or knocked unconsious, she simply returns to the intercom. This is caused by allowing Colonel Autumn to escape, though the actual cause might be automatic dialouge scripting glitches.
 * If Sarah Lyons performs the above action, it is also possible (if you save outside the Rotunda door) to uninstall Broken Steel and then Reinstall it. This is helpful if you are using the Enclave Hellfire Armor and Heavy Incinerator and do not want to lose them as I did my first try with the above attempt.
 * A blast from a mini-nuke or exploding car can cause Liberty Prime to shoot up into the air and remain stuck several dozen feet up. If this happens, the player should clear any enemies in the immediate area and Liberty Prime should return to the ground. Otherwise, you should load a previous save.
 * Jericho might follow you inside the chamber. This is slightly humorous as when you pass out, he remarks: 'Come on! Let's get moving!'.
 * If the player continuously walks into Lyons it is possible to trap her inside the Purifier. If you push her in far enough and shoot her until she turns aggressive and then push the airlock button she will run out as it's closing and run down the stairs. The game then freezes for a few seconds and the screen turns white with the radiation bar still showing.
 * The multiple blasts and fireworks may cause some screen & textures problems, displaying strange effects in the sky and on the ground during the battle, causing the game to eventually freeze. This could force you to restart your console. If experiencing this kind of problem, save the game when bugs are starting and then reloading it right after may resolve it.
 * While Liberty Prime is being raised out of the lab if you quickly run out to the courtyard and fast travel to the Citadel (even though you're already inside) Liberty Prime will automatically be standing where he normally would. If you run past him and continue to the bridge where the force-field is he will not follow, thus you cannot continue the mission because he won't be able to destroy the force-fields or the one around the Jefferson Memorial (an easy way to fix this is by loading an earlier game, preferably in the lab, then once in the courtyard walk to the entrance instead of fast traveling there) Note:walking to the entrance is slower than fast traveling to the front but it wont glitch your game.
 * An unknown bug causes the Airlock to not be locked in the quest list. With the Broken Steel DLC, the quest still remains after waking up in the Citadel. The only way to fix this is to reload an earlier save.
 * If you start the "Head of State" Quest, you may see the Brahmin from the Temple of Union. If you kill it, then either continue or go away from fast travel, Liberty Prime may find Hannibal, Caleb, and the rest of them hostile and kill them. You will get the message saying "Hannibal and Caleb have died" and failed the quest.
 * Sarah Lyons may not be killed, and a glitch may occur where you knock her out, and drag her into the Purifier. If you close the door, she will wake up non-hostile, and you can talk to her and tell her to turn it on, or you will do it.
 * If you tell your companion to wait in the rotunda while the purifier is activated, they will not be there on return trips to the rotunda (due to the area being instanced), nor will they be in their usual meeting place after they are fired. In order to reacquire your companion, you must use the console command player.moveto , instruct your companion to follow you, then exit the monument. A solution for 360 or PS3 users, is you can simply leave the Capital wasteland via The Pitt or Point Lookout. Your companions would be fired and waiting in their usual spot, and return to the Capital Wasteland and re-hire them. If you have Mothership Zeta DLC, it may also be possible to go to Mothership Zeta and have the follower on the ground upon your return but there is no sure way of knowing.
 * Also for the above bug, if it happens on xbox, make sure your followers are in the airlock before you activate it. This will prevent the above bug.
 * if Sarah Lyons is sent in, and made hostile before the bulkhead is opened, she will exit the airlock. if you then open the bulkhead, she will die as if she has activated the purifier, while still being on the outer walkway.
 * Your follower(s), including Sarah, will continuously shoot at Colonel Autumn even though he is dead and you can't loot his body or finish the mission.

Ending Movies
The ending movie varies depending on how the player plays the game, and some of the largest differences are seen depending on what the player has done during Take it Back! See Fallout 3 endings for more info.

Summary
Take It Back! is the final main quest, with the game ending immediately after its completion (unless you have the add-on Broken Steel).

Behind the scenes

 * Liberty Prime in Take it Back! is an example of the plot device known as Chekhov's gun, because it is introduced as a background element early on in the story, but its purpose and reason for existence are not revealed until needed.
 * Liberty Prime's spheroid head with glowing light eyes closely resembles Gort, Klaatu's robot, from The Day the Earth Stood Still (1951).