Wikipedia
Oathkeeper
"Oathkeeper" is the fourth episode of the fourth season of HBO's fantasy television series Game of Thrones, and the 34th overall. The episode was written by Bryan Cogman, and directed by Michelle MacLaren. It aired on April 27, 2014. The title refers to the new sword gifted to Brienne of Tarth by Jaime Lannister and the themes of duty that propels the episode. The episode focuses on the aftermath of Joffrey's wedding, the Night's Watch's attempt to deal with the mutineers, and Daenerys' continued conquest of Meereen. "Oathkeeper" also featured the debut appearance of the Night King, a leader of the White Walkers, though he was not identified as such until the following year.