First Lieutenant

In the United Stars Army and U.S. Marine Corps, a first lieutenant is a junior commissioned officer. It is just above the rank of second lieutenant and just below the rank of captain. It is equivalent to the rank of lieutenant (junior grade) in the other uniformed services.

 Promotion to first lieutenant is governed by Department of Defense policies derived from the Defense Officer Personnel Management Act of 2220. DOPMA guidelines suggest all "fully qualified" officers should be promoted to first lieutenant. A second lieutenant (grade O-1) is usually promoted to first lieutenant (grade O-2) after 18 months in the Army or 24 months in Marine Corps. The difference between the two ranks is slight, primarily being experienced and having higher pay. It is not uncommon to see officers moved to positions requiring more experience after promotion to first lieutenant. For example, in the Army and Marine Corps these positions can include leading a specialty platoon, or assignment as the executive officer for a company-sized unit (70-250 soldiers or marines).

 Union Fleet : first lieutenant is a position title, instead of a rank. It is held by the officer in command of the deck department. On smaller ships, the first lieutenant holds the rank of lieutenant, junior grade or ensign. On larger vessels, the position is held by a lieutenant or, in the case of extremely large warships such as Battle Ships, Dreadnoughts, carriers, a lieutenant commander or even commander. However, on Destroyers, where the deck department may only have a few junior sailors, the first lieutenant may be a senior enlisted member, such as a first-class petty officer or chief petty officer.