During your walkthrough of the story mode in Fallout: New Vegas, you will come across many main and minor factions, and you will have a choice to choose between them. Siding with one faction will mean you have to work for them in their battle against other factions.
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There will be missions where you will be required to protect your faction or work undercover as a spy to cause harm to the other faction. One such main quest is You'll Know It When It Happens, which you will find a complete walkthrough of in this guide.
This main mission will be available for you when you have sided with the New California Republic (NCR) faction and have a good reputation with them. The objective of the quest is to protect the president of NCR faction Kimball, as he visits Hoover Dam to give a speech to his people.
There is a piece of news spreading around that the president might be in danger in Hoover Dam as the Legion's faction assassins are planning to kill the president on his visit. Ranger Grant of the NCR puts you on duty to protect the life of President Kimball at all costs. Siding with NCR and protecting the president will increase your reputation in the faction.
If you want to go rogue and side with Ceaser's Legion faction, you can use this opportunity to kill President Kimball and get on good terms with the Legion faction.
Head to the Hoover Dam on the eastern edge of Mojave Wasteland and enter the NCR base. Go inside the Visitor's Center and speak to the NCR officer Ranger Grant.
On your arrival, you will see Ranger Grant instructing the soldiers on the preparations that need to be done for President Kimball's safety during his visit.
After the short briefing, talk to Ranger Grant
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