In the United States Army, U.S. Marine Corps, and U.S. Air Force, a lieutenant colonel is a field grade military officer rank just above the rank of major and just below the rank of colonel. It is equivalent to the naval rank of commander in the other uniformed services.
The pay grade for the rank of lieutenant colonel is O-5. In the United States armed forces, the insignia for the rank consists of a silver oak leaf, with slight stylized differences between the Army/Air Force version and the Navy/Marine Corps version.
Promotion to lieutenant colonel is governed by Department of Defense policies derived from the Defense Officer Personnel Management Act (DOPMA) of 1980 for officers in the Active Component and its companion Reserve Officer Personnel Management Act (ROPMA) for officers in the Reserve Component (e.g., Reserve and National Guard). DOPMA guidelines suggest 70% of majors should be promoted to lieutenant colonel after serving a minimum of three years at their present rank and after attaining 15–17 years of cumulative commissioned service.
While often written as "Lt. Colonel" in orders and signature blocks, as a courtesy, lieutenant colonels are addressed simply as "colonel" verbally and in the salutation of correspondence. The U.S. Army uses the three letter abbreviation "LTC." The United States Marine Corps and U.S. Air Force use the abbreviations "LtCol" and "Lt Col" (note the space) respectively.
The U.S. Government Printing Office recommends the abbreviation "LTC" for U.S. Army usage, "LtCol" for Marine Corps usage, and "Lt. Col." for the Air Force. The Associated Press Stylebook recommends the abbreviation "Lt. Col." for the Army, Marine Corps, and Air Force.
Slang terms for the rank historically used by the U.S. military include "light colonel", "short colonel", "light bird", "half colonel", "bottlecap colonel" (referring to the silver oak leaf insignia), and "telephone colonel" (from self-reference as "colonel" when using a telephone).
The rank of lieutenant colonel has existed in the British Army since at least the 16th century and was used in both American colonial militia and colonial regular regiments. The Continental Army continued the British and colonial use of the rank of lieutenant colonel, as the second-in-command to a colonel commanding a regiment. The lieutenant colonel was sometimes known as "lieutenant to the colonel."
In British practice, regiments were actually commanded by their lieutenant colonels, as the colonel was a titular position (with the incumbent absent from the regiment serving as a senior staff officer, a general officer, or as a member of the nobility). Since the British colonel was not a "combat" officer, beginning in May 1778 to simplify prisoner of war exchanges, American regiments began to eliminate colonels by attrition and replace them with a lieutenant colonel commandant. The conversion was never completely effected and some regiments remained commanded by colonels throughout the war. From 1784 until 1791, there was only one lieutenant colonel in the US Army (Josiah Harmar), who acted as the army's commanding officer.
In the Continental Army aides to the Commander in Chief, viz., Lieutenant General George Washington, were lieutenant colonels. Additionally, certain officers serving under the Adjutant General, Inspector General, and Judge Advocate General, ranked as lieutenant colonels.
During the 19th century, lieutenant colonel was often a terminal rank for many officers, since the rank of "full colonel" was considered extremely prestigious reserved only for the most successful officers. Upon the outbreak of the Civil War, the rank of lieutenant colonel became much more common and was used as a "stepping stone" for officers who commanded small regiments or battalions and were expected, by default, to be promoted to full colonel once the manpower of a regiment grew in strength. Such was the case of Joshua Lawrence Chamberlain, who commanded a Maine regiment as both a lieutenant colonel and later as a colonel.
After the Civil War ended, those officers remaining in the United States Armed Forces found lieutenant colonel to again be a terminal rank, although many lieutenant colonels were raised to higher positions in a brevet status. Such was the case with George A. Custer, who was a lieutenant colonel in the regular army, but held the brevet rank of major general.
The 20th century saw lieutenant colonel in its present-day status although, during the 1930s, many officers again found the rank to be terminal as the rank of colonel was reserved for only a select few officers.
In the United States Army and the United States Marine Corps (USMC), a lieutenant colonel typically commands a battalion/squadron-sized unit (300 to 1,200 Soldiers/Marines), with a major as second-in-command and a command sergeant major/sergeant major (USMC) as principal NCO or senior enlisted adviser (SEA). A lieutenant colonel may also serve as a brigade/brigade combat team, regiment/regimental combat team, Marine Aviation Group (MAG), Marine Expeditionary Unit (MEU), or battalion task force executive officer. Lieutenant colonels routinely serve as principal staff officers, under a colonel as chief of staff, on a general staff ("G" staff) of a division, Marine Expeditionary Brigade (MEB), Marine Aircraft Wing (MAW), or Marine Logistics Group (MLG). These staff positions may include: G-1 (administration and personnel), G-2 (intelligence), G-3 (operations), G-4 (logistics), G-5 (civil/military affairs), or G-6 (computers and communications). Usage of "The G-n" may refer to either a specific staff section or the staff officer leading a section. Lieutenant colonels may also be junior staff at a variety of higher echelons.
In the United States Air Force, a lieutenant colonel is generally a squadron commander in the operations group, mission support and maintenance groups, or a squadron commander or division chief in a medical group. Lieutenant colonels may also serve on general staffs and may be the heads of some wing staff departments.
In US Army and Air Force ROTC detachments, the commanding officer is typically a lieutenant colonel, along with several majors, captains, and non-commissioned officers serving as assistants. However, some detachments are commanded by full colonels.
The rank of lieutenant colonel is also used by many large American police departments for officers in senior administrative positions. The rank is not always called "lieutenant colonel," and in many cases - particularly with municipal police agencies - an alternate term such as "assistant chief" or "commander" is used, and only the insignia is retained. In some organizations, however, especially state police agencies, both the title and insignia are used. Occasionally, the rank is used in conjunction with, rather than instead of, an official title. For example, in the Texas Department of Public Safety, the head of the agency's patrol division is titled "Chief of the Highway Patrol", but holds the rank of a lieutenant colonel: this figure is thus referred to as "lieutenant colonel," not "chief".