|Talk to General Oliver.|
|(Optional) Flush the Legion invaders through the turbines.|
|Make your way through the power plant and across the dam.|
|Arrive at the Legion camp across the bridge, speak to Legate Lanius.|
|By passing a Speech or Barter check (100), the player can convince the Legate not to fight.||Otherwise, the player will have to defeat the Legate.|
|Once he is defeated, speak with General Oliver.|
After completing You'll Know It When It Happens, at the very moment the Courier might choose to side with the NCR for the final battle (thus completing For the Republic, Part 2), the player character will be automatically taken from Col. Moore's office to General Oliver's compound, where the General will begin a briefing. The Courier is given the chance to wait, as this begins the end quest for the game. If the player chooses to continue, after the briefing, Legion members attack the Hoover Dam and you need to fight your way through the power plant rooms and head east toward their base. You will start in power plant 04.
- (Optional) Mike Lawson will speak to you. If you wish to follow his suggestion and do the optional part which involves flushing the Legion invaders through the turbines, agree to his suggestion. To complete the optional part of the quest, follow the staircase immediately to the left in power plant 04 then across the room to enter power plant 03. The console is on the second floor of power plant 03, on the southern wall. Passing a Science check (65) allows the player to use the terminal to engage the turbines. Completing this will require manual intervention; return to power plant 04 by the closest door which is right below the console. On the second floor on the east wall, from where you reenter there is an exit to the Dam exterior. The manual release valve you need to complete this part of the quest is along the river to your left between the broken retainer wall, just after the second sandbag wall. Return to power plant 03.
Proceed to power plant 02, then power plant 01, dispatching Legion troops on your way. Climb the stairs on your left in power plant 01, then proceed north along the balcony. Follow the passage along the left, then go up the stairs, and exit via the elevator to the Hoover Dam visitor center. At this point, you will begin to notice assistance appearing from companions and factions you have helped out along the way. Exit via the double doors on the east side to Hoover Dam.
Proceed to the north along the curved walkway above the dam. There is a door hidden in the side of the dam that you can pick with a Lockpick skill of 75 (hard). Enter the Hoover Dam checkpoint. From here, you can check the terminal; if you have a Science skill of 100 and a detonator, you may use the terminal to detonate one group of legions (the blast is centered near the first tower). When you exit on the other side, you will encounter a squad of NCR Veteran Rangers. Their commander will thank you for your support and ask you how to coordinate their assistance. The player can respond with several dialogue choices which lead to the following actions:
- The Rangers snipe Legion soldiers for you;
- The Rangers follow you into battle;
- The Rangers will pave the way for the player (requires a Speech check of 85);
- Rangers will fall back, providing no assistance.
After crossing the dam, head left along the bridge to the east, and continue, following the road. Enter the gate to the Legate's Camp. Head east into the camp, following the path up the side of the ridge. There, you will encounter Legate Lanius. Note that with a Speech or Barter skill of 100, you can pass a series of skill checks, and avoid fighting him. The Legate is extremely challenging, and many Legionaries will come out and attack you. If you pass all of the previous speech checks and fail the last one, you get another Speech challenge  which can convince the Legate to fight you one on one - all the other Legion troops will become friendly to you.
- There is another tree of answers in dialogue with Lanius - the speech checks that suggest bluffing. This way is actually easier, because it does not require level 100 Speech (checks are 60-75-90-90). In the last Speech check all three answers give the same result, but after it you must choose the <lie> answer, and the Legate will flee.
After either killing the Legate, or passing a series of speech checks to end the fight peacefully, you should notice the gate to the camp has closed. Head back to it. The gate will explode and you will meet with General Oliver.
- If you lost your companions during your travels, they will be teleported back to you for the battle.
- If you have enlisted the help of the Boomers and recovered the B-29 from Lake Mead, the bomber will be seen flying from the south over the Dam when you come out of the turbine building, and will bomb the area in front of you. It will then fly off to the north towards Nellis.
- Likewise, if you have convinced the Boomers to assist you and the NCR, Boomer howitzers at Nellis will provide fire support.
- If you have completed For Auld Lang Syne, the Vertibird will appear after leaving the Hoover Dam Checkpoint and the members of the Remnants who agreed to help will assist you with the battle on foot. If you convinced them to assist the Legion, however, they will be hostile. This has since been fixed by patch 220.127.116.112.
- If the Enclave Remnants participate in the battle, Cannibal Johnson will follow you to the Legate's Camp and help you fight Lanius.
- If the Brotherhood of Steel has agreed to help the NCR during the battle, two paladins will assist you in power plant 04. Oddly, they'll sometimes have T-45d power armor instead of the common T-51b.
- If you have convinced the Great Khans to aid the NCR, they will be outside helping the NCR. One will approach you stating that they came just in time.
- If The Followers of The Apocalypse agreed to be medics for the war you'll find Followers' First Aid Boxes scattered throughout the level.
- If you told Arcade Gannon to support the Remnants at Hoover Dam (at the end of the mission "For Auld Lang Syne"), he will appear in his father's Tesla power armor fighting the Legion in the Visitor Center. He will stay in this area and won't follow you.
- When exiting the visitor center, the engineer who intended to kill President Kimball may still be outside in which he will take out his knife and rush to attack the Legion. You can search his body for the failsafe detonator.
- Just like with all the other end-game quests, you will receive XP at the end of Eureka (which suggests Obsidian wanted to allow players to continue after the end of The Second Battle of Hoover Dam).
Behind the scenesEdit
"Eureka" is the state motto of California. The word comes from the ancient Greek word, heúrēka, literally meaning "I have found". There is a story of the famous Greek mathematician Archimedes, who shouted "Eureka!" upon making a great discovery and ran naked through the streets of Syracuse.
- PC Playstation 3 Xbox 360 Occasionally, leaving Power Plant 1, you will randomly fail 'Don't Tread on the Bear!' and all NCR forces will go hostile to you. [verified]
- Playstation 3 Xbox 360 If you stay back until the Legate has killed both NCR Rangers, he will not talk to the player on his own. That gives you the possibility for a sneak kill. [verified]
- Playstation 3 Xbox 360 Sometimes the Legate will not register as dead and you cannot continue with the quest. POSSIBLE Fix: If you go through the speech checks and convince him to fight you one-on-one, he will register as dead and you can continue the quest. Killing all the other Legion troops might fix this problem as well. [verified]
- PC Using setstage 00136166 100 spawned none of the needed minions to continue the mission regardless of the fact that the player has progressed and done all available side missions and fought through to the legates camp (as the previous mission had bugged). [verified]
- PC If the final missions have bugged out while trying to help the NCR (as happens if you complete Wild Card: Side Bets before For The Republic Part 2), you can use setstage "00136166" 100. You then fight your way to the legate camp but Legate Lanius won't appear. You can then use setstage "00133075" 20 and General Lee will appear as you go to leave the legate camp, thereby starting the endgame sequence. [verified]
- Playstation 3 The Legate has been known to flee once the two NCR Rangers appear, he will go out of the main gate, and you cannot follow him as the gate will have no sense of interaction. [verified]
- Xbox 360 There is a glitch where you will be able to fast travel out of the dam and camp, but cant reenter being the area is sealed off. Making it impossible to finish the quest. SOLUTION: a weak solution to this problem: If you want to fast travel, you must enter an area that you can not fast travel from (house, building, tent, etc.) and exit it again. Immediately upon loading outside, you must press the pip-boy button and you will be able to fast travel, but then you must repeat the processes again after arriving at the next destination. This allows you to continue the quest. [verified]
- Playstation 3 Xbox 360 It is possible for a companion to become effectively trapped in Oliver's compound. this is due to the fact it become labeled "locked requires key". This means the trapped companion cannot follow you. For some odd reason they will not teleport as usual when you go through a loading screen door. This was experienced with Veronica Santangelo and Rex as a companion. Rex followed as normal. [verified]
- Playstation 3 Xbox 360 Even after you kill Legate the quest marker will remain on him until all of Caesar's Legion in the area are dead. This can some times break the quest as the legion in the area are effectively stored in an unreachable area to the left of the main building were you encounter legate. This can be fixed via explosives such as rockets to kill them via blast radius. [verified]
- Playstation 3 It is possible for the player to fast travel when this quest is in progress by simply going through the hoover dam checkpoint and straight after you come out quickly go to your pipboy and fast travel. WARNING after doing this you will have to use that same method if you want to fast travel again. [verified]
- Xbox 360 It is possible that, while fighting the Legate, a glitch may cause him to suddenly "fly" straight up into the air almost beyond the point of visibility before plummeting back down to the ground, killing him on impact, thus winning the fight and the game for you. (This glitch was only observed after many, many failed attempts at killing him and restarting from the last save-point.) [verified]
- Playstation 3 Xbox 360 If you are using weapons with high rates of fires, being around others with high ROF weapons may cause severe frame rate lag or freezes. [verified]
- Xbox 360 Sometimes, if you completed Oh My Papa for the NCR, by assassinating Papa Khan the Great Khans that appear to assist you will be invisible and attempting to target them in V.A.T.S. will cause the game to freeze. [verified]