Operation : Sunburst Operation : Sunburst was a military conflict during the NCR - Brotherhood War in 2276 . Background . The leader of the Mojave chapter of the Brotherhood , Elijah , ordered troops under his command to seize HELIOS One , a pre - War Poseidon Energy solar plant , after acquiring information about a possible weapons system hidden in or connected to the facility . The Brotherhood presence at the facility eventually drew the attention of the New California Republic Army , which had begun deploying to the Mojave " en masse " to secure Hoover Dam and New Vegas . With the establishment of a regional stronghold at Camp McCarran , NCR command decided to seize Helios One to both secure U . S . Route 93 and procure another source of electrical power in the Mojave . Although the power plant was hardly defensible , leaving Brotherhood forces exposed to attack on all sides ( save a small canyon leading to Hidden Valley ) , Elder Elijah ordered his troops to dig in and protect him as he attempted to unlock the secret of the facility . Battle . NCR Army forces stormed the power plant in 2276 . While Brotherhood troops were able to defend themselves with their advanced weaponry , equipment and power armor , the NCR Army outnumbered them heavily and had the facility surrounded , granting them a significant numerical and tactical advantage . The NCR could afford to lose more troops than the Brotherhood , and was set on capturing the facility . Due to the overwhelming number of NCR soldiers , the Brotherhood Paladins began to sustain heavy losses , making it even more difficult to fight from the poorly defensible position . Although Head Paladin McNamara repeatedly asked Elder Elijah to call for a tactical retreat in order to save the lives of his men , he adamantly refused , insisting that he had almost unlocked the secret of the facility : the Archimedes weapon system . However , Elijah did not anticipate that he would be unable to use the orbital weapons , as he did not possess Euclid ' s C - Finder , the tool necessary to aim and fire Archimedes II . The only device he had access to was the previous generation orbital defense system , which was useless as it was preset for test firing within the confines of the Helios One perimeter . Frustrated , Elder Elijah abandoned the men and women under his command and disappeared into the wastes . Forced to assume command as Elijah deserted , McNamara wasted no time in gathering the survivors and leading a retreat to Hidden Valley from Helios One , but not before reactivating the pre - War security measures inside the solar collection tower to prevent the NCR from picking up on Elijah ' s research . The NCR Army had won the battle , though , and inflicted a serious defeat on the Mojave chapter of the Brotherhood of Steel . Aftermath . The NCR Army was preoccupied with securing Helios One and did not think of launching a second offensive to finish off the Brotherhood until the surviving members had long since disappeared into Hidden Valley . Aware that the Brotherhood and Caesar ' s Legion were both in the area , the NCR garrison hunkered down and worked to get the power back on . Senior officers like Colonel Cassandra Moore longed for the chance to find and destroy the remaining members of the Brotherhood in the Mojave , but could not find a way to do so without weakening the NCR ' s position at Helios One and risking an attack by the Legion . As a result , a stalemate developed , with the NCR and the Brotherhood still at war , but effectively unable to attack one another . With their former leader gone , McNamara assumed command in accordance with the Brotherhood ' s chain of command protocols . In order to prevent an accidental disclosure of the location of Hidden Valley , their sole remaining stronghold in the Mojave , the new Elder declared a full lockdown in effect . Activity outside the bunker was drastically restricted ; only supply runs , occasional reconnaissance missions and night patrols were allowed to leave the underground installation , and even then , they were strictly forbidden to engage NCR Army units . The lockdown order remained in effect for five years , until 2281 , when a broken air filtration system forced the Brotherhood to either commit themselves to destruction or become active once again . Though the Brotherhood ' s ascetic lifestyle had prepared its members for a sequestered existence , the passivity of the current situation proved highly stressful . The NCR ' s attempts to restore power at the HELIOS One facility were complicated by the NCR ' s severe lack of qualified scientists , technicians and engineers . In the process of looking for anyone at all who could work on the facility , an incompetent chem - addict was hired to act as the facility ' s principal engineer . He was unable to bring the facility to even moderate operational status , leaving it at 1 % efficiency . Ignacio Rivas was assigned by the Followers of the Apocalypse to independently research the facility and ensure that the man hired by the NCR would not figure out a way to unlock the facility ' s dark secrets . Appearances . Operation : Sunburst is mentioned only in " " and its " Dead Money " .