The End of Days is a religious concept mentioned within the Book of Revelation. Supposedly, a day will come when the end of an old world will give birth to a new world. Travis Marshall sought to bring about this Armageddon by enacting religious Tableaus deciphered from notes taken on the Book of Revelation.Travis believed that seven sacrifices would trigger the End of Days, and the world would go through a drastic change. Of course, this outcome was disputed from a scientific point of view. Regardless, the actions of Travis created a legion of followers.
According to the Book of Revelation, on the 1260th day following the appearance of the Two Witnesses, the End will be triggered. Also, "the Beast" will overcome and kill the Witnesses before they are resurrected. On the show, the date is Monday, November 28th, 2011, the date of a solar eclipse.
On the top of a skyscraper, Travis attempted to complete the prophecy by slaughtering Harrison Morgan (Dexter's son) as the "Lamb." Just in time, Dexter Morgan arrived to save Harrison's life. Dexter subdued Travis, who was unable to kill "The Beast." At this point, the eclipse occurred, and the world remained intact afterward.
In conclusion, Travis was unsuccessful in bringing about the End of Days, but "The Beast" did succeed in "slaying the Witness" when Travis's life was taken by Dexter's blade, ironically inside a church. ("This is the Way the World Ends")
The story continues into Season Seven.