Second lieutenant
From Halopedia, the Halo wiki
Template:Rank Infobox Second Lieutenant is a junior/company grade commissioned officer rank of the UNSC Marine Corps. It is the lowest commissioned officer rank, and is equal in rank to Ensign in the UNSC Navy. They command platoon sized units.
Second Lieutenant is typically the entry-level rank for most commissioned officers in the UNSC Marine Corps. A Second Lieutenant usually receives a promotion to First Lieutenant after 18 to 24 months service.
In informal settings, Second Lieutenants are referred to simply as "Lieutenant".