A battalion is a military unit, typically consisting of up to one thousand soldiers commanded by a lieutenant colonel and subdivided into a number of companies, each typically commanded by a major or a captain. The typical battalion is built from three operational companies, one weapons company and one headquarters company. In some countries, battalions are exclusively infantry, while in others battalions are unit-level organisations.
A company is a military unit, typically consisting of 100–250 soldiers and usually commanded by a major or a captain. Most companies are formed of three to seven platoons, although the exact number may vary by country, unit type, and structure.
Military ranks are a system of hierarchical relationships, within armed forces, police, intelligence agencies or other institutions organized along military lines. The military rank system defines dominance, authority, and responsibility in a military hierarchy. It incorporates the principles of exercising power and authority into the military chain of command—the succession of commanders superior to subordinates through which command is exercised. The military chain of command constructs an important component for organized collective action.
A brigade is a major tactical military formation that typically comprises three to six battalions plus supporting elements. It is roughly equivalent to an enlarged or reinforced regiment. Two or more brigades may constitute a division.
Commander is a common naval officer rank as well as a job title in many armies. Commander is also used as a rank or title in other formal organizations, including several police forces. In several countries this naval rank is termed frigate captain.
An aide-de-camp is a personal assistant or secretary to a person of high rank, usually a senior military, police or government officer, or to a member of a royal family or a head of state.
Captain general is a high military rank of general officer grade, and a gubernatorial title.
An executive officer is a person who is principally responsible for leading all or part of an organization, although the exact nature of the role varies depending on the organization. In many militaries and police forces, an executive officer, or "XO", is the second-in-command, reporting to the commanding officer. The XO is typically responsible for the management of day-to-day activities, freeing the commander to concentrate on strategy and planning the unit's next move.
Adjutant is a military appointment given to an officer who assists the commanding officer with unit administration, mostly the management of human resources in an army unit. The term adjudant is used in French-speaking armed forces as a non-commissioned officer rank similar to a staff sergeant or warrant officer but is not equivalent to the role or appointment of an adjutant.
Second-in-command is a title denoting that the holder of the title is the second-highest authority within a certain organisation.
Commandant is a title often given to the officer in charge of a military training establishment or academy. This usage is common in English-speaking nations. In some countries it may be a military or police rank. It is also often used to refer to the commander of a military prison or prison camp.
United States military seniority is the method by which the United States Armed Forces determines precedence among commissioned officers, in particular those who hold the same rank. Seniority is used to determine assignments, tactical commands, promotions and general courtesy. To a lesser extent, historical seniority is used to recognize status of honor given to early United States military leaders such as inaugural holders of certain ranks or those officers who served as leadership during major wars and armed conflicts.
A limited duty officer (LDO) is an officer in the United States Navy or United States Marine Corps who was selected for commissioning based on skill and expertise. They are the primary manpower source for technically specific billets not best suited for traditional Unrestricted Line, Restricted Line, or Staff Corps career path officers. Per Title 10, U.S. Code, an LDO is a permanent commissioned officer appointed under section 8139 in a permanent grade above chief warrant officer, W-5, and designated for limited duty.
In the United States Army, Marine Corps, Air Force and Space Force, major is a field officer above the rank of captain and below the rank of lieutenant colonel. It is equivalent to the naval rank of lieutenant commander in the other uniformed services. Although lieutenant commanders are considered junior officers by their services, the rank of major is that of a senior officer in the United States Army, the United States Marine Corps, and the United States Air Force.
In the uniformed services of the United States, captain is a commissioned-officer rank. In keeping with the traditions of the militaries of most nations, the rank varies between the services, being a senior rank in the naval services and a junior rank in the ground and air forces. Many fire departments and police departments in the United States also use the rank of captain as an officer in a specific unit.
The United States Marine Corps is organized within the Department of the Navy, which is led by the Secretary of the Navy (SECNAV). The most senior Marine commissioned officer is the Commandant of the Marine Corps, responsible for organizing, recruiting, training, and equipping the Marine Corps so that it is ready for operation under the command of the unified combatant commanders. The Marine Corps is organized into four principal subdivisions: Headquarters Marine Corps, the Operating Forces, the Supporting Establishment, and the Marine Forces Reserve.
In the United States, commander is a military rank that is also sometimes used as a military billet title—the designation of someone who manages living quarters or a base—depending on the branch of service. It is also used as a rank or title in non-military organizations, particularly in law enforcement.
A ship's company or complement comprises all officers, non-commissioned officers and enlisted personnel aboard a naval vessel, excluding civilians and guests.
In the U.S. Army (USA), U.S. Marine Corps (USMC), U.S. Air Force (USAF), and U.S. Space Force (USSF), captain is a company-grade officer rank, with the pay grade of O-3. It ranks above first lieutenant and below major. It is equivalent to the rank of lieutenant in the Navy/Coast Guard officer rank system and is different from the higher Navy/Coast Guard rank of captain. The insignia for the rank consists of two silver bars, with slight stylized differences between the Army/Air Force version and the Marine Corps version.
