First lieutenant

First Lieutenant is a military rank. A traditional infantry rank, First Lieutenant is 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 is equivalent to Lieutenant junior grade.

This rank was used by the United States armed forces and police, represented by a single rectangular silver bar uniform insignia. 1st 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).

A US Marine 1st Lt. assigned to aircraft carrier USS Enterprise (CVN-65) was one of the troops involved in the hunt for intruding time traveller Pavel Chekov in 1986.

In an alternate timeline where Na'kuhl time-travellers had allied themselves with Adolf Hitler's Nazis in 1944, an Obersturmführer First Lieutenant named Ghrath was executive officer to Vosk.

From Memory Alpha -- the free Star Trek reference