Take it Back!

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

Attack!
When you reach The Citadel, you will hear Owyn Lyons, and his daughter talking about the assault. They will ask Scribe Rothchild about Liberty Prime, and they will power him up.

Prime is launched in a rather stereotypical way for superweapons as seen in movies, TV Shows, and such, 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, the Brotherhood's massive Mini-Nuke-tossing, laser-armed robot Liberty Prime will be hoisted out of the Citadel on a crane and the Lyons' Pride will dutifully follow it, as should the player. Once outside the Citadel, the monstrous machine will begin stomping its way to the fallen bridge. There is a Raider hideout under the broken bridge, but they end up being killed very quickly by the Lyons' Pride. 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. Unfortunately, Liberty Prime will not clean up all resistance, so the player must do some mopping up. Liberty Prime, thankfully, is a powerful anti-aircraft weapon, so the player doesn't need to waste time and munitions trying to down the incoming Vertibirds. 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. The ground troops are the only threat to the player, as they are usually spaced out enough to avoid being wiped out all at once by the Mini-Nuke blasts. 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.

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.

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 requires a high Speech skill. After conceding defeat, he will tell the player he will leave him or her to their fate. After this, Sarah Lyons will give a short remark on the player's decision, depending on his or her Karma.


 * Fight Colonel Autumn. The Colonel isn't terribly hard to defeat, but his bodyguards are tougher.

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!

Now, the game has the player make one final decision:

End Game Choices
 NOTE: This section becomes Choices if you have downloaded Broken Steel 

Decision 1: Self-sacrifice or sacrifice another.
Damage to Project Purity has resulted in an incredible radiation buildup that will overwhelm anyone who is in the chamber during activation regardless of whatever preventative measures they have taken (e.g. Rad Away, Rad-X, or Radiation Resistance).

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. This can be verified by forcing Sentinel Lyons to start the Purifier (your character tells her the passcode in dialog).

Choices
There are only two choices of who activates Project Purity: the player character or Sentinel Lyons. If players ask their companions to assist, they will refuse even if they are immune to radiation and bound to the player's command, such as Sergeant RL-3 or Charon. Activating the console will be fatal to the person inside the chamber, as it was to James. The medicine that saved Colonel Autumn from the same fate cannot be obtained during the game.

Companion Responses

 * Fawkes

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."

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 that "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.


 * Dogmeat

In addition, a new dialog option with Dogmeat 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 in response whines. As intelligent as the canine may be, there is no option to have Dogmeat activate Project Purity.


 * Sergeant RL-3

Even if you took Sergeant RL-3 (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:

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

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

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

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


 * Star Paladin Cross

She respectfully refuses of course:


 * Clover

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


 * Jericho

Jericho also refuses, stating simply:

Decision 2: Project Impurity.
If the player still has in their possession the Modified FEV created by President Eden, they can insert it into the water filter. As in Fallout 2, by design 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.

Note: Inserting the Modified FEV lowers Karma by 1000; however starting the purifier raises it by 1000, thus no change in Karma.

Note: Inserting the Modified FEV has a long-term game impact if you have downloaded the Broken Steel add-on. The Broken Steel add-on introduces Aqua Pura item (similar to Purified Water) but every time you drink the Aqua Pura, a warning will come up that reads 'Continued consumption of FEV-laced water will be fatal'.

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. 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 game ends here. However, if Broken Steel has been installed, you will still see the regular ending, but your character then wakes up two weeks later at the Citadel. You can also convince your followers to activate the Purifier, at least those which are naturally resistant to radiation (Charon, Fawkes, Sergeant RL-3). However, if you choose to do nothing and let the Purifier explode, the game still ends.

As you wake up, you encounter Elder Owyn 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. (Confirmed on 360)
 * It is possible to kill Colonel Autumn before initiating the dialog cutscene when heading into the purifier room. If you're lucky you can stall before the dialog within the room and kill Autumn before the scene occurs.  Doing this will also cause all remaining Enclave to become friendly in the room, but you will not be able to communicate with either of them except for a friendly Hello or Hi.  This can also cause untimed/overlapped dialog when Sentinel Lyons is talking to Doctor Li. After that the game can continue normally as if you answered to kill Colonel Autumn. (unconfirmed)
 * 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. (confirmed on PC - as mentioned, loading a previous save will also work)
 * 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 I haven't found a way to get the Lyons Pride to continue. (unconfirmed)
 * After leaving the Citadel, Liberty Prime may just stop moving altogether. If this happens, reload an earlier save and he should start to move. (unconfirmed)
 * Sometimes randomly in the battle, all the soldiers will return to the citadel (most of the time when one of them die in battle) and Liberty prime will disappear. (unconfirmed)
 * When you are in the courtyard of the citadel and began to move out to began your attack the screen will instantly freeze, If you fast travel and go back to the citadel Liberty Prime will not move and stay still meaning there is no end to the game. (unconfirmed)
 * It's possible for the game to randomly freeze during initial invasion, it could be caused by moving too far away from the Pride. (unconfirmed)
 * 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. (PC: Confirmed to solve the problem, however after the dialogue between the player and the 'spawned' Sarah Lyons, the original Sarah and followers (Fawkes and Dogmeat) then emerged through the doorway, resulting in two Sarah Lyons. Original Sarah initiated dialogue with the player and asked why they were hesitating to enter the purifier.) Can also be solved by quicksaving on the PC in the Rotunda and then quickloading. (confirmed PC)
 * 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 Comand player.placeatme 0001d44e.  (unconfirmed)
 * 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.

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).

Trivia

 * Liberty Prime may be a pun on Optimus Prime from the Transformers series. One of his quotes, "Freedom is the sovereign right of every American!", plays off Prime's famous "Freedom is the right of all sentient beings," as well.
 * 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.