Who Dares Wins

Who Dares Wins is the final Fallout 3 main quest and achievement that is added to the game in the Broken Steel add-on.

Detailed walkthrough
Paladin Tristan has tasked you with infiltrating the Enclave's final, massive base at Adams Air Force Base, and destroying it with an orbital strike. The quest begins at White House Plaza. The utility tunnel that leads to the White House now also has a connection to the Presidential metro, which should lead directly to Adams Air Force Base. Reach White House Plaza through any means you have, and enter the tunnels. The metro is crawling with feral ghouls, Mister Gutsies and sentry bots. You'll proceed down several different tunnels before meeting with M.A.R.Go.T., the protector, and dispatcher of the metro. The robots (and M.A.R.Go.T, to some extent) are initially hostile, but if you pass a difficult Speech or Science check, or present a valid Senate employee ID, M.A.R.Go.T will mark you as friendly, and you'll have a chance to use her for information or help.

Contain the Security Breach
Among other things, you can learn that the train to Adams is offline, due to a "security breach" which has resulted in "the forced removal of a main fuse." M.A.R.Go.T can repair the fuse and train, but only if the breach is contained. According to her, the intruders have depleted 22% of the metro security units, have no internal body heat, and are emitting lethal levels of radiation. The metro units should be able to handle the breach at lower player character levels, but higher levels can result in facing several more deadly foes, which will make short work of the sentry bots, and you too, if you aren't careful. If you aid in containing the breach, the Presidential metro sentinal [sic] unit will repair the Adams tram for you; if not, you can find the main fuse on its body, as well as in the room with the fuse box, and can use it and a Repair check to fix the train yourself.

Enter Adams Air Force Base
After a quick ride on the train, you'll wind up in the Adams metro station. Continue through the tunnels, and you'll encounter the first of many Enclave soldiers in Adams. Reach the surface, climb the stairs, and take a left to find the "Resupply Crate" Tristan mentioned. Inside is a fully repaired Tesla cannon, 50 electron charge packs, 50 microfusion cells, and your orders, contained within a voice recording, courtesy of Tristan. There is also a dead robobrain nearby containing a few energy cells.

Proceed to the right, and begin the long trek to the mobile base crawler. The path is full of Enclave troops, regular and Hellfire, banks of turrets, deathclaws, and several combat-ready Vertibirds. Make use of the Tesla cannon to destroy the vertibirds in one shot, and anything else (guns, grenades, followers, even several Enclave artillery batteries) to stave off the Enclave hordes. As you approach your next objective, you'll begin to see vertibirds gunning down the runway, lasers firing in all directions. They're firing on a contingent of Brotherhood soldiers, who are the "distraction" Tristan promised. It doesn't work very well, though, as the Brotherhood soldiers are outnumbered, outgunned, and hold the low ground.

Find the access terminal to lower the ramp on the Mobile Platform
The mobile base crawler can only be entered via a ramp. To lower the ramp, you'll need to enter the Air Traffic Control Tower and find the Main Access terminal. When you reach the main battlefield on the runway, take a right, and enter the small building through a set of stairs on the west side. Inside are a few Enclave robots, which can range from robobrains to sentry bots, depending on your level. When you reach the top, activate the unlocked terminal and hit the "Lower Access Ramp" entry. Beware, though, that as you enter the control tower, three vertibirds will appear overhead, the last of which fires three missiles straight at the tower. The resulting explosions could easily cripple or kill you, so it is best to take cover on the stairs. Alternatively, you can shoot down the vertibirds with the Tesla cannon, if you act quickly enough.

Enter the Enclave Mobile Platform
Make your way back down to the runway, and head on over to the ramp. There are several more Enclave troops, but a Brotherhood of Steel task force will arrive and cover you. Run up the ramp, and enter the final Enclave stronghold.

Destroy the Enclave Mobile Platform with an Orbital Strike
The first thing you come across is an Enclave Repulsion Field. Using the blue panel to the left, you can deactivate it (Science 80), set a timed charge (Explosives 50), or smash the control panel. Smashing the panel will cause an explosion (which will damage you), as will setting the charge (the difference being that you have time to escape). Either way, the field will still be partially active, and passing through it will cause damage. If deactivated with Science, the field will be harmless.

Turning left will introduce you to Enclave Squad Sigma after an alarm goes off. Turning right and heading into the repair bay yields plenty of ammunition, as well as an encounter with Stiggs, who fixes the robots. Talking with him gives some useful information:
 * The floor above is a deathclaw research facility, but the majority are out fighting in checkpoints across the Wastes.
 * The facility is patrolled by robots, who are all controlled through a mainframe, located on the floor above, in the middle.
 * To reach the Satellite Tower, you have to reach the Central Control Area, then to the Launch Platform. After the platform, you'll have to fight or sneak (if you can) through a few Enclave soldiers to reach the tower.

Heading up the ladder in the repair bay or the stairs where Sigma Squad attacked will lead to the second level. Your target is the mainframe in the center of the floor. The deathclaw research facility should contain one or two Enclave-controlled deathclaws, which will be a great asset if you still have the deathclaw control scrambler. The mainframe is locked behind several "High Clearance" doors, which can only be opened with a High Clearance keycard. The various Enclave officers each carry one, which will open all the doors. The mainframe itself is divided into two sections: Door control and Robot control. The door control terminal is unlocked and can be used to unlock any doors on the floor, the Armory, and the doors leading to the Platform. The Robot terminal is locked Hard, but if hacked, you can deactivate all the robots, or scramble their targeting parameters. If you have the Robotics Expert perk, you can even reverse the friend-or-foe settings, marking the Enclave as hostile, and yourself as friendly.

Head to the Satellite Tower. Once inside, head to the top, to the terminal. Make sure you've thoroughly searched the crawler, then hit "Fire Payload" and choose your target:
 * Preset Target 01: Citadel
 * Preset Target 02: Project Purity
 * Preset Target 03: Megaton
 * Preset Target 04: Rivet City Carrier
 * Preset Target 05: Adams AFB Platform

Only two of the targets can be fired upon: Adams AFB Platform, or the Citadel. Be warned, anything in the Crawler will be lost forever, no matter which choice you make, so clear it out before you make the decision. Once you make your choice, unlock the door from the active terminal to your right, and head through the door at the top back outside, where a Brotherhood of Steel vertibird lands to get you out. If Sentinel Lyons survived the activation of Project Purity, she will personally escort you to the vertibird.

If you chose the Citadel: You are rewarded with 1000 negative karma, and on the flight back the pilots seem to think the vertibird is malfunctioning when the Citadel won't respond to radio. Upon landing and seeing the smoldering ruins, they quickly pick up that it was you, and attempt to kill you, deeming you a traitor and a murderer. Any other Brotherhood of Steel members you meet, like in the Washington Monument, GNR building, White House Plaza, Arlington Library, and the Jefferson Memorial, will be hostile as well. You also can enter the Citadel's hidden armory, filled with plenty of goodies such as Tesla cannons, alien power cells, Nuka-grenades, mini nukes, and Callahan's Magnum.

If you chose Adams AFB Platform: You are rewarded with 1000 positive karma, and the vertibird lands a little off Adams AFB to allow you to watch the missiles strike. After hopping back on the vertibird, you are taken to the Citadel, where Elder Lyons is waiting with a heart-warming speech of thanks. You may then speak with Scribe Rothchild and Paladin Tristan for two additional unmarked quests. You are also allowed to return to Adams AFB after the quest where there are 8 Tesla cannons spread about in 4 different Resupply Crates. Three Dog will also occasionally make a funny report about your deeds and tell his "children" to have pity on the Enclave; they're homeless after all!

Reward

 * 1500 XP
 * Tesla cannon
 * ±1000 Karma

Behind the scenes
"Who Dares Wins" is the regimental motto of the British Special Air Service (SAS) special forces, coined by the founder David Stirling. One of their main roles (and the role for which they were originally conceived) during the Second World War was the destruction of Axis aircraft and positions at airbases behind enemy lines in North Africa. The saying comes from the similar Latin expressions, "Qui audet vincit" and "Qui audet adipiscitur."

Bugs

 * After clearing the area of ghouls, the (optional) quest of containing the security breach may not trigger as complete, preventing the Presidential Sentinel Unit from repairing the train. If playing on the PC, this can be fixed by opening the console and entering or .  If those commands do not work, another alternative is to  then kill previously slain ghouls until the required number of ghouls have been killed (the script requires 21 ghouls killed in total). Alternatively, you can destroy the Presidential Sentinel Unit, take the fuses from its body, and do the repairs yourself. Be warned that destroying it will turn all the other surviving robots hostile. To avoid this, use V.A.T.S. to disable its combat inhibitor, and the other robots will actually assist you in destroying it.
 * Sentinel Lyons will mention the first time she met the Lone Wanderer, outside the GNR building, even if the player bypasses that part of the main quest entirely.
 * Should you destroy the Citadel, the Brotherhood Initiate will yell "Kill this traitor, kill him!", even to a female character.
 * Sometimes, when you pick up the high security clearance cards they will not appear in your Pip-Boy.
 * After the platform has been blown up and you returned to the Citadel, Sentinel Lyons may just walk away instead of starting her speech, and you are stuck unable to move. Use the console command and start talking to her to finish the quest.

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