It is obtained when one completes the campaign mission Sierra 117 on the Normal, Heroic, or Legendary difficulty. In Halo: The Master Chief Collection, it is possible to get this achievement on Easy.
The Halo 3 achievement gives the player 20 Gamerscore and is represented by a blue plate with the Roman numeral I on it.
Note: You must complete the whole level through from the start; a halfway rally point will not count.
Trivia[]
The name of this achievement could be a reference to the short film, Halo: Landfall. In Halo: Landfall, Marines are in search for John-117's location when he falls to Earth.
Gallery[]
The Achievement art showcasing the level, Sierra 117.