Legion of Honor
From Halopedia, the Halo wiki
The Red Legion of Honor, sometimes referred to simply as the UNSC Legion of Honor, is an award given to UNSC soldiers for selfless acts of heroism in combat. The incodent must involve acts where one soldier chooses to put this or her life on the line in order to save his or her commrades. The medal is usually awarded in a ceremony.
John-117 won one of these by diving into a bunker full of Covenant, taking out twenty of them by himself, saving a platoon of Marines pinned down by a Shade.