Second lieutenant

Second Lieutenant is a junior commissioned officer rank of the UNSC Marine Corps and UNSC Army. It is the lowest commissioned officer rank, and is equal in rank to Ensign in the UNSC Navy. They are given command of platoons, such as the case of 2nd Lieutenant Oros in Halo: The Flood.

Second Lieutenant is typically an entry-level rank for most commissioned officers. 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" or "Lt.".