(covers information from several alternate timelines)
First lieutenant was a military rank. A traditional infantry rank, first lieutenant was the second lowest officer grade, senior to a second lieutenant. Infantry lieutenants fall below captains, and command a platoon, consisting of about thirty troops. In comparison to naval ranking systems, a first lieutenant was equivalent to lieutenant junior grade. Prior to the late 19th century, in the British navy, first lieutenant referred to a position, a ship's most senior lieutenant serving as second in command, rather than to a rank.
First lieutenants existed in other Earth nations, such as World War II Germany. In the German armies, this was translated as Oberleutnant, but in the SS, first lieutenants were referred to as Obersturmführer ("senior storm leader"). The collar insignia for this was a black square bordered with white, with three silver pips in a diagonal line above a doubled silver stripe (a single pip was also worn on each epaulet).
In an alternate timeline in which Na'kuhl time-travelers had allied themselves with Adolf Hitler's Nazis in 1944, an Obersturmführer first lieutenant named Ghrath was executive officer to Vosk. (ENT: "Storm Front")
A US Marine Marine lieutenant assigned to the aircraft carrier USS Enterprise (CVN-65) was one of the troops involved in the hunt for intruding time traveler Pavel Chekov in 1986. (Star Trek IV: The Voyage Home)
|Enlisted personnel||Commissioned officers||Generals and flag officers|
|ENS||LT JG||LT||LT CMDR||CMDR||CAPT||FCAPT||CDORE||RADM||VADM||ADM||FADM|
|2nd LT||1st LT||CAPT||MAJ||LT COL||COL||BRIG||MAJ GEN||LT GEN||GEN||MARSHAL|
|Services:||Andorian • Bajoran • Cardassian • Ferengi • Human (CSA • SS • UE MACO • USA) • Jem'Hadar • Klingon • Romulan • United Earth/Federation Starfleet • Vulcan|
Mirror universe: Terran Empire Starfleet • Terran Empire MACO
The Marine 1st lt. was played by Donald W. Zautcke, an actual USMC officer.
According to the Star Trek Encyclopedia (4th ed., vol. 2, p. 9), 1st lieutenant was a rank in the Military Assault Command Operations in the 2150s. The insignia for this rank was on display in a diagram of MACO ranks and insignia.