Liberty Prime Liberty Prime ( later Liberty Prime Mark II if rebuilt ) is a unique U . S . Army robot 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 . Background . Liberty Prime is a formidable combat robot that is currently in the possession of the Brotherhood of Steel . Its original intent was to liberate Anchorage , 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 . The Citadel laboratory computer terminal , located directly in front of Liberty Prime , also reveals that the project was commissioned by General Constantine Chase as a joint effort between the U . S . Army , General Atomics International and RobCo Industries . However , problems with the power system caused major delays . These delays consumed so much time that Anchorage was ultimately liberated in a much longer and more costly battle using the United States Army ' s " other " secret weapon : the T - 51b power armor . 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 mutant s 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 . Gameplay attributes . 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 , including 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 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 . Notable quotes . Many of its quotes give reference to ' 50s and ' 60s anti - communist slogans , made to be more specific to China . Appearances . Liberty Prime appears in " Fallout 3 " , its add - on , " Broken Steel " , " Fallout 4 " and is mentioned in the " Automatron " add - on . Bugs . " Fallout 4 " . Liberty Prime often stops right before the body of water on the way to the Institute .