Tactical assessment: Red Chinese victory... impossible.
Liberty Prime (later Liberty Prime Mark II if rebuilt) is a unique U.S. Armyrobot found at the Citadel. It stands 40 feet (12.19 meters) tall and is armed with a powerful eye laser and tactical nuclear bombs, making it a major combat asset.
Liberty Prime was found and brought to working order by the Brotherhood of Steel. Its total restoration was due to the assistance of Dr. Madison Li, who solved Prime's power issues in the year 2277. After its destruction at the Satellite relay station in the same year it remained in disrepair until 2287, where it is then in the process of being restored to assist the Brotherhood division in Boston.
Liberty Prime is a formidable combat robot that is currently in the possession of the Brotherhood of Steel. Its original intent was to liberateAnchorage, Alaska, from the Red Chinese during the Sino-American War of 2072. It is programmed to deliver a mixture of patriotic propaganda messages and incredible firepower to ensure victory. Although it could still have been deployed, its combat subroutines weren't online during the war. All it would be able to do is step on the Chinese troops, according to a letter from Dr. Bloomfield to General Chase found in the Citadel Laboratory terminal entries.
Roughly two centuries later, Liberty Prime was finally salvaged and brought into service by the Brotherhood of Steel after they discovered it in the basement of the destroyed Pentagon. The Brotherhood was able to modify Prime's targeting system to perceive Enclave forces and super mutants to be Chinese communists.
Liberty Prime required a tremendous amount of energy to operate. The Brotherhood of Steel was unable to provide the necessary amount of power, even with the advanced technology salvaged from inside the Pentagon. Eventually, with the aid of Dr. Li, the Brotherhood of Steel solved the problem.
Liberty Prime was the Brotherhood's trump card against the Enclave, and was revealed when it marched on Project Purity where it was used to effortlessly destroy the Enclave defenders entrenched there. For two weeks afterward, Liberty Prime helped the Brotherhood prevail in the war against the Enclave, but was eventually destroyed by an orbital warhead bombardment at the Enclave-held satellite relay station. Liberty Prime's remains were recovered by the Brotherhood of Steel and, though it would take months or years to do so, the Brotherhood set about rebuilding and upgrading it. Meanwhile, Rothchild immediately began work on rebuilding Prime, hoping to restore him to working condition. Ten years later, in 2287 the project was still far from being completed, as the Brotherhood lacked crucial components necessary for him to operate. When Elder Arthur Maxson realized that the Institute can be tracked down and confronted in the Commonwealth, Prime's components were loaded onto the Prydwen and brought along for the campaign. A special gantry was constructed in the ruins of the Boston Airport, to assemble the war machine under Proctor Ingram's orders - as long as the Brotherhood would be able to find the missing parts.
Liberty Prime fires dual, head-mounted energy beams, which are similar to shots fired from a Tesla cannon. The beams can kill multiple Enclave soldiers with a single shot. Its backpack holds a seemingly inexhaustible supply of explosives that it hurls at enemies with unerring accuracy. These munitions detonate on contact, in a manner very similar to a mini nuke, but with many times the explosive power. Liberty Prime's massive size and strength count as weapons too, as it can crush or rip to shreds anything in its path, if it doesn't blast them to bits first. Prime is immune to all kinds of conventional attacks, being able to withstand barrage of mini nukes with no damage and is able defeat energy barriers simply by walking into them, although he will sometimes grab them and rip them down. Finally, to inspire his allies and demoralize foes, he constantly spouts anti-communist phrases as well as declaring that "American democracy cannot be defeated". Like most of the robots in the game it seems unaware that any time has passed between 2077 and the present or, more accurately, that any cataclysmic or world-changing events have transpired.
When Liberty Prime is brought back online at the Boston Airport in 2287 after his destruction in the line of duty, the Brotherhood of Steel has already implemented several upgrades to his systems, such as improved electromagnetic motivators for his limbs. They have therefore designated him as 'Mk. II', a designation he has willingly accepted into his programming. Other changes include his eye laser - which now fires a single massive red beam instead of a salvo of blue beams - as well as a lifetime supply of more modern Mark 28 nuclear bombs for Prime to hurl at his enemies after completing the quest Liberty Reprimed. The latter he now does with markedly increased frequency to the point where Prime almost completely foregoes the use of his eye laser in favor of his nukes, which he tosses at pretty much anything he considers a target, even if it is just a lonely raider toting a base Pipe pistol. Liberty Prime MK II also demonstrates a significantly greater understanding of battlefield tactics than his predecessor; switching from a land-based route to an amphibious assault during his attack on the Institute whereas before he only demonstrated the capacity to overcome straightforward obstacles such as energy barriers. Prime was also able to correctly deduce that the Institute was a subterranean complex and utilized his laser weapon to bore a tunnel directly into the Institute. However, it is unknown whether Prime was always capable of performing such complex maneuvers or if they were installed by the Brotherhood as part of his MK II refit. Together, these changes easily make Liberty Prime the most powerful NPC in Fallout 4 as he is capable of killing almost any enemy at any level with only one or two attacks. Since he is entirely immune to his own weaponry, and well aware of the fact, he has no qualms about using his nukes at point-blank range, should he find himself faced with enemies milling around his feet. In such a case he displays complete disregard for any collateral damage to his allies, who are therefore advised to maintain a healthy distance from the massive robot at all times. Other than that, not much has changed in Prime's overall behavior - he still believes he is fighting for the liberation of Anchorage from Chinese forces and continues to broadcast anti-communist propaganda slogans in the most thunderous way possible while he carves an irradiated swath through the incinerated remains of his enemies.
Take it Back!: The Brotherhood of Steel, with the help of Dr. Li, manages to fix the power issues with the robot. With the pressing need to reclaim Project Purity, Elder Lyons orders Prime deployed without proper testing. Liberty Prime makes its way to the Jefferson Memorial, while destroying Enclave energy barriers, vertibirds and troops. Once there, Liberty Prime assists the Brotherhood in guarding the Memorial's entrance, after taking down the force field surrounding it. The giant robot will then remain there for the duration of the quest.
Death From Above: Liberty Prime joins the Lone Wanderer in the assault on the Satellite Relay Station, an Enclave base located beyond the Rockland Car Tunnel. After the Enclave hits Prime with an orbital strike, Prime crawls from the wreckage and initiates its self-destruct sequence to prevent being captured by the "communists". Its head, feet and what appears to be a forearm are taken back to the Citadel. Similar to Deputy Weld, its head can be activated, which will cause it to play back some of its anti-communist phrases, although they sound much more garbled than they are during Take it Back!.
Ad Victoriam: With Liberty Prime fully operational, the Brotherhood of Steel is ready to launch their assault on the Institute. The Sole Survivor is to follow Liberty Prime to the C.I.T. ruins, and put an end to the Institute.
Airship Down: After the Institute and Sole Survivor has dealt with the Railroad in End of the Line, the Institute will initiate their final assault against the Brotherhood of Steel. To take down the Prydwen, the Institute created a computer virus that will reprogram Liberty Prime's targeting system. After they push back the heavy resistance and the computer virus is uploaded, Liberty Prime will target the Prydwen as an aerial communist incursion and shoot the airship down. The wreckage of the Prydwen subsequently lands on Boston Airport, destroying both the Brotherhood outpost and Liberty Prime.
Liberty Prime is first seen in the lab beneath the Citadel in its inactive state. The Lone Wanderer can gain information about the robot, as well as hear some of its dialogue by using a nearby computer terminal to initiate a dialogue test.
In an e-mail from RobCo Industries to the US Army, it is revealed that although there are power management issues, it may still be possible to send Liberty Prime to Anchorage in time for the attack, although it is only possible if the Army were to disable all of Prime's weapon systems. Later in the e-mail, it is proposed that "Maybe he could just step on them?" instead.
If the Lone Wanderer watches Liberty Prime as it is being lifted out of the Citadel lab, Liberty Prime will hit the wall of the Citadel, subsequently causing a loud "thud" sound and dislodging some pieces of the wall.
Although the Lone Wanderer can't kill Liberty Prime, it's possible to cause it to turn hostile towards the Lone Wanderer, in which case it will eliminate the player character and their followers in a matter of seconds.
Although the player character may hear it make comments about the liberation of Anchorage, Liberty Prime never actually appears in, or is mentioned in the Operation: Anchorageadd-on, as it was not completed in time.
After Broken Steel is completed, you can find Liberty Prime's head on the table in the Citadel lab. However, upon returning to the Satellite Relay Station where he was destroyed, you can still find his head there.
Although it is said that he is programmed to attack super mutants, he will not attack the super mutant companion Fawkes. However, if Fawkes is fired in the area of Liberty Prime, Prime will fire upon the Super Mutant.
The impact data set for Liberty Prime's weaponry is available as legacy content in Fallout: New Vegas, available for use in the G.E.C.K.
When Liberty Prime is reconstructed in Fallout 4 it lacks the chest, abdomen, leg and shoulder armor which was present in its previous appearance.
If the Sole Survivor sides with the Brotherhood, Liberty Prime will be found patrolling Boston Airport after the endgame.
During Ad Victoriam, when Liberty Prime reaches Bunker Hill he recognizes it as a memorial site and engages "patriotism subroutines" and pauses to salute while saying "honoring the fallen is the duty of every red-blooded American".
In Fallout 4, it is possible to target Liberty Prime in V.A.T.S.. Liberty Prime, however, is immune to any form of damage, much like in Fallout 3. As well, he never turns hostile against the player if shot at.
The following is based on unverified behind the scenes information and has not been confirmed by canon sources.
Liberty Prime throws football-shaped mini-nukes as if it were a quarterback. This pays homage to "The Nuclear Football", which is a term used to refer to the briefcase containing the launch codes for America's nuclear arsenal, with the president as the football's "quarterback".
Liberty Prime's head design strongly echoes Gort, the powerful robotic protector from the 1951 anti-nuclear-war science-fiction movie The Day the Earth Stood Still. Both robots share a powerful beam attack from their visor-like "eyes".
End of information based on unverified behind the scenes information.
ps3pcxbox360 Liberty Prime often gets stuck. Although the most common places for this glitch is on the left side of the highway when heading to retake the Purifier at the Jefferson Memorial, and on the first large bridge the Lone Wanderer crosses. [verified]
pc If all else fails, you may be able to fix this by selecting Liberty Prime in the console and typing "moveto player".
pcxbox360 If you kill Vargas at any point in the game before starting Take it Back!, Liberty Prime will stay immobile, preventing the player from continuing the quest line. [verified]
pc The only way to fix this issue is using the console command: player.placeatme 0001d44e 1 to respawn Paladin Vargas and proceed with the quest.
xbox360 It is possible to get around this by baiting Liberty Prime into chasing after you by attacking BoS initiates.
ps3 Liberty Prime may launch into the air and remain there. The best way to solve this is to wait (real time). If this fails, the player may need to reload the previous auto save. [verified]
ps3xbox360 If the Lone Wanderer manages to get far enough ahead of Prime when it is attacking Enclave forces, it is possible for the player character to be killed by its attacks. [verified]
ps3 If the Lone Wanderer manages to get too far ahead of Liberty Prime before it disables the first "force field", Liberty Prime may stop walking across the first bridge after shutting down the first "force field." [verified]