Ad Victoriam Ad Victoriam is a Brotherhood of Steel main quest and an achievement / trophy in " Fallout 4 " . Detailed walkthrough . After destroying the Railroad and getting the beryllium agitator , speak to Proctor Ingram at the Boston Airport . She will now allow you to power up Liberty Prime . Go to the top of the gantry and plug the agitator into Liberty Prime . After that , return to Ingram and press the button . Liberty Prime will activate , leave the gantry and start walking towards the C . I . T . ruins , with the Brotherhood of Steel personnel saluting it as it walks away . You must now follow Liberty Prime as it walks through the ruins of Boston to reach the Institute . As it reaches the East Boston Preparatory School , synth s will be teleported to attack it . From that point on , you will encounter various enemies : raiders , super mutants ( including one or two behemoths ) , and synths . Due to a broken bridge , Liberty Prime will have to cross through the water in order to continue . Liberty Prime will reach the Bunker Hill monument , and after a brief salute to the memorial , Liberty Prime will continue its journey through the streets of Boston . Liberty Prime will annihilate everything thrown at it , using its powerful eye laser as well as nukes , even effortlessly crushing the behemoths that will attack the robot near Ticonderoga . Do note however that , unlike in Take it Back ! , Liberty Prime will mostly use its Mark 28 bombs rather than its eye laser ; thus , it is advised to stand back from Prime ' s enemies and let it destroy them , as you may get caught in the blast radius of one of Prime ' s bombs , which will deal a significant amount of damage if it does not kill you . Since 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 . During your trip to the Institute , you will be followed by a small group of Brotherhood of Steel knights , comprised of Knight Lucia and a few unnamed Brotherhood of Steel members , as well as a vertibird . Eventually , Prime reaches the CIT ruins , which are guarded by a large group of synths . At this point , Elder Maxson , armed with his unique weapon , as well as more Brotherhood of Steel personnel , will join in the fight . Liberty Prime will analyze the area and detect the Institute , and proceed to use his weaponry to create an access . While Prime uses his eye laser and nukes to create an access , he will be unable to attack the synths , meaning you will have to deal with them , although Maxson ' s gatling laser often makes short work of them . After some time , Prime will throw nukes at the front of the ruins , creating a hole that will allow the Brotherhood of Steel to gain direct access to the Institute . Jump down the hole to enter the Institute , completing this quest and starting the next one , The Nuclear Option . Behind the scenes . " Ad Victoriam " is an accusative construct in Latin ; ad being a preposition that is paired with an accusative , " ad " having the meaning meaning ' toward ' , and victoriam being the accusative form of the noun " Victoria , ae " , a first declension feminine noun meaning ' victory ' , translating to : ' toward victory ' . Brotherhood of Steel members in " Fallout 4 " often use this quote , during combat or to celebrate victory .