Lockdown (medal)
From Halopedia, the Halo wiki
Lockdown is a medal in Halo 5: Guardians. It is awarded for every third Stronghold Secured Medal earned in one life. The Stronghold Secured Medal is itself earned by entering a friendly-controlled Stronghold partially captured by the enemy and has no enemies inside (or being in such a stronghold when the last enemy leaves or dies), which erases their capture progress.
