Indonesia
In Indonesia, "first lieutenant" is known as ''Letnan Satu'' (''Lettu''), Indonesian National Armed Forces uses this rank across all three of its services. It is just above the rank of second lieutenant and just below the rank of Captain (armed forces), captain.Israel
In the Israel Defense Forces, the rank above second lieutenant is simply lieutenant. The rank of (קצין מקצועי אקדמאי (קמ"א (''katsín miktsoí akademai'' or "kama"), a professional academic officer (that is, a medical, dental or veterinary officer, a justice officer or a religious officer), is equivalent to a professional officer of the second class in the reserve and equivalent to first lieutenant.United Kingdom
British Army
In the British Army and Royal Marines, the rank above second lieutenant is simply lieutenant (pronounced ''lef-tenant''), with no ordinal attached. Before 1871, when the whole British Army switched to using the current rank of "lieutenant", the Royal Artillery, Royal Engineers and fusilier regiments used "first lieutenant" and "second lieutenant".Royal Navy
The ''first lieutenant'' (often abbreviated "1st Lt") in a Royal Navy ship is a post or appointment, rather than a rank. Historically the lieutenants in a ship were ranked in accordance with seniority, with the most senior being termed the first lieutenant and acting as the second-in-command, unless the ship was complemented with a Commander (Royal Navy), commander. Although lieutenants are no longer ranked by seniority, the post of "first lieutenant" remains. In minor war vessels, destroyers, frigates, and submarines, the ''first lieutenant'' is second in command, executive officer (XO) and head of the executive branch; in larger ships where a commander of the warfare specialization is appointed as the executive officer, a ''first lieutenant'' is appointed as their deputy. The post of ''first lieutenant'' in a shore establishment carries a similar responsibility to the ''first lieutenant'' of a capital ship. Colloquial terms in the Royal Navy for the ''first lieutenant'' include "Number One (Royal Navy), number one", "the jimmy" (or "jimmy the one") and "James the First" (a back-formation referring to James I of England).Partridge, p 612, p 621, p 884 The first lieutenant may hold the rank of sub-lieutenant, lieutenant or lieutenant-commander.United States
U.S. Army, U.S. Marine Corps, U.S. Air Force, and U.S. Space Force
In the United States Army, U.S. Army, United States Marine Corps, U.S. Marine Corps, United States Air Force, U.S. Air Force, and United States Space Force, U.S. Space Force, a first lieutenant is a juniorU.S. Navy and U.S. Coast Guard
In the United States Navy, U.S. Navy and United States Coast Guard, U.S. Coast Guard, "first lieutenant" is the name of a billet and position title, rather than rank. Officers aboard early sailing ships were the captain and a number of lieutenants. The senior among those lieutenants was known as the first lieutenant, and would have assumed command if the captain were absent or incapacitated. As modern ships have become more complex, requiring specialized knowledge of engineering, communications, and weapons, the "first lieutenant" is the officer in command of the deck department responsible for rope, line handling during Mooring (watercraft), mooring and underway replenishment. On smaller ships, the officer of the "first lieutenant" billet holds the rank of lieutenant, junior grade or Ensign (rank), ensign. On larger vessels, the position of "first lieutenant" is held by a lieutenant or, in the case of extremely large warships such as cruisers or aircraft carriers, the position of "first lieutenant" may be held by a Lieutenant Commander (United States), lieutenant commander or even Commander (United States), commander. However, on submarines and in aircraft squadrons, where the deck department may only have a few junior sailors, the "first lieutenant" billet may be filled by a first-class petty officer or chief petty officer. What is known in the U.S. Navy as the "first lieutenant division" is usually composed of junior sailors (E-3 and below) who are completing their ninety days of temporary assigned duty, or TAD, that all enlisted personnel are required to perform when initially assigned to a command. The primary mission of the division is servicing, cleaning, organizing and inventorying items within a command.Barnebey, Matthew; "1st Lieutenant Division plays significant role in supporting base", ''Jax Air News''Cutler and Cutler, p.90U.S. Revenue Cutter Service
The term "first lieutenant" had a dual meaning in the United States Revenue Cutter Service (known until 1894 as the United States Revenue-Marine). The position title of first lieutenant was held by a junior officer who was in charge of deck operations and gunnery. The rank of first lieutenant was the equivalent of lieutenant in the current rank structure of the U.S. Coast Guard, U.S. Navy, United States Public Health Service Commissioned Corps, and National Oceanic and Atmospheric Administration Commissioned Officer Corps. The next senior officer ranking above first lieutenant was captain and the next two lower officer ranks were second and third lieutenant, respectively. When the Revenue Cutter Service merged with the United States Life-Saving Service to form the U.S. Coast Guard in 1915, the rank of first lieutenant carried over into Coast Guard and remained in use until 1918, when the Coast Guard adopted the rank structure of the U.S. Navy.Cipra, Dave; "A History of Sea Service Ranks & Titles", ''Commandant's Bulletin'', (May, June, July 1985), U.S. Coast Guard Historian's Office.Gallery
Army
Marines
Navy
Air Force
Space Force
Notes
;Citations ;References used * * * * * {{US officer ranks, collapse=collapsed Military ranks of the British Army Royal Navy appointments Military ranks of the United States Army Officer ranks of the United States Air Force Officer ranks of the United States Space Force Military ranks of the United States Marine Corps