From Halopedia, the Halo wiki
UNSC Marine Corps
Armor protected firepower and shock action
The 506th Tank Regiment was a UNSC Marine Corps armored regiment.
The 506th fought during the Battle of Earth, at the Battle of Mombasa. During the battle, they were charged with making a path to the Southern Bridge Span, despite overwhelming forces in their path. They successfully achieved their mission.
Several years later, the regiment's actions were honored as several replicas of the 506th's tanks were included in the John-117 Memorial at the Museum of Humanity.