It is obtained when the player completes the Halo 3 Campaign on the Normal difficulty. This Achievement gives 125 Gamerpoints to the player. It can be obtained through either co-op or single player, or a combination of the two. If a player completes the Halo 3 campaign on the Heroic or Legendary difficulty without this achievement already earned, they will be unlocked together.
It is represented by a shield with the Marathon symbol and one Combat knife across it; the same as the normal difficulty symbol.