Lieutenant
From Starbase 900 Wiki
Lieutenant (typically pronounced as "loo-tenant") is a military rank, the equivalent of which is used by the service organizations of many civilizations. As a traditional naval rank, Lieutenant is the grade between Ensign and Lieutenant Commander. In the Marine Corps, Lieutenant is the lowest officer grade, falling below Marine Captain. An infantry Lieutenant commands a platoon, consisting of about thirty troops.
Starfleet lieutenants are expected to be effective small-section leaders and technical experts, developing their leadership skills in preparation for promotion to the commander tier.