Oban

 is a human planet that was originally used as a secret military training area prior to its colonization as an agrarian world. It is the location of the Halo 4 DLC map, Daybreak.

History
At some point after the Human-Covenant war, the Office of Naval Intelligence found and secured Oban as a top secret military facility. Outposts and bases were established in the planet's mountains. After extensive classified ops the planet was colonized as a farm-world.

Trivia

 * Oban is named after a town on the coast of Scotland. It has been noted by members of 343i and Certain Affinity that the planet resembles the Scottish Highlands.
 * It is possible that Oban was not terraformed.