自由至尊 (被再次重建后称作自由至尊MKII) 是一架独一无二的美军军用机器人found at the Citadel. 它身高12.2米，全副武裝with a powerful eye laser and tactical nuclear bombs, making it a 戰鬥機器人。
自由至尊號于2277年被鋼鐵兄弟會在大本營找到。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, when it was brought to Boston for restoration and activation.
自由至尊是一台强大的战斗机器人，目前由钢铁兄弟会拥有。自由至尊號原本目的是為美國軍隊在2072年中美战争期间从中國手中收復阿拉斯加的安克雷奇。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.
修复完成的自由至尊was the Brotherhood's trump card against the Enclave, and在净水器之战中派上了大用场，把英克雷揍了个惨。此后的两个星期，自由至尊帮助兄弟会在与英克雷的战争中取得了胜利，但在一次战斗中，自由至尊被驻守atellite relay station的英克雷呼叫的轨道轰炸摧毁。自由至尊的残骸被钢铁兄弟会收回，尽管这样做可能要花费数月或数年，但兄弟会还是着手对其进行重建和升级。Meanwhile, Rothchild immediately began work on rebuilding Prime, hoping to restore him to working condition.
十年后的2287年，自由至尊的修复工作依然处于瓶颈期，因为兄弟会缺少了一块至关重要的拼图——用来启动自由至尊的“燃料”。当Elder Arthur Maxson意识到realized that the Institute can be tracked down and confronted in the Commonwealth，自由至尊的零件被装载到了普利德温号上随兄弟会一起到达了联邦。兄弟会在战前的波士顿机场中建造一个特殊的龙门架，to assemble the war machine under Proctor Ingram's orders - 找到那个至关重要的零件。
自由至尊號的頭部裝備了鐳射武器，單發就能消滅不少敵人，which are similar to shots fired from a Tesla cannon. 它背後裝置的核彈還可以自行向敵人投擲，其供應取之不盡，用之不竭，而且威力相當於迷你核彈的好幾倍。自由至尊號巨大的體型和武器裝備的實力足以證明：它可以將擋在前面的任何東西撕成碎片……即使是用腳踩。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, 為了激發它的盟友和分化瓦解敵人，它還會不斷喊出各種口號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, including an almost complete redesign of his limbs and arms which has replaced old liquid-feed hydraulic systems with electromagnetic actuators. 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 Liberty Prime 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.
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.
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 player character may hear it make comments about the liberation of Anchorage, Liberty Prime never actually appears in the Operation: Anchorage add-on.
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 on in the area of Liberty Prime, Prime will fire upon the super mutant.
Despite being an anti-communist super-weapon, the symbol on his right shoulder shows a striking resemblance to the Korean People's Army Air Force (North Korean Air Force) roundel.
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", pausing 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.
Despite being immune to all forms of damage, in Fallout 4, he has a death animation. Upon death, he will fall onto his knees and then spring forward after a few seconds.
In Fallout 4, if the Sole Survivor turns on the Brotherhood of Steel after completing their storyline, and then takes down the Prydwen during With Our Powers Combined, Liberty Prime will actually survive the fight against the Minutemen.
The Sole Survivor can be trampled underfoot if they are in his path.
Many of its quotes give reference to '50s and '60s anti-communist slogans, made to be more specific to China.
"Liberty Prime is online. All systems nominal. Weapons hot. Mission: the destruction of any and all Chinese communists."
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".
自由至尊的頭部造型灵感来源于1951年美国科幻电影地球停转之日中的机器人Gort。Both robots share a powerful beam attack from their visor-like "eyes".
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. [已核实]
If all else fails, you may be able to fix this by selecting Liberty Prime in the console and typing "moveto player".
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. [已核实]
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.
It is possible to get around this by baiting Liberty Prime into chasing after you by attacking BoS initiates.
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. [已核实]
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. [已核实]
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." [已核实]
Liberty Prime often stops right before the body of water on the way to the Institute. [已核实]