Military rank Military ranks are a system of hierarchical relationships in armed forces , police , intelligence agencies or other institutions organized along military lines . Usually , uniforms denote the bearer ' s rank by particular insignia affixed to the uniforms . Ranking systems have been known for most of military history to be advantageous for military operations , in particular with regards to logistics , command , and coordination ; as time continued and military operations became larger and more complex , military ranks increased and ranking systems themselves became more complex . Within modern armed forces , the use of ranks is almost universal . Communist states have sometimes abolished rank ( e . g . , the Soviet Red Army 1918 – 1935 , the Chinese People ' s Liberation Army 1965 – 1988 , and the Albanian Army 1966 – 1991 ) , only to re - establish them after encountering operational difficulties of command and control . Ancient and medieval ranks . Greek ranks . From 501 BC the Athenians annually elected ten individuals to the rank of " strategos " , one for each of the ten " tribes " that had been created with the founding of the democracy . Strategos literally means " strategist " which was considered the army leader and so it is usually translated as " general " . Originally these generals worked together with the old " polemarch os " ( " warlord " ) but over time the latter figure was absorbed into the generalship : each of the ten generals would rotate as polemarch for one day , and during this day his vote would serve as tie - breaker if necessary . The ten generals were equal to one another ; there was no hierarchy among them , however a basic form of democracy was in effect : For example , at the Battle of Marathon in 490 BC , the generals determined the battle plan by majority vote . Particular assignments , however , might have been given to individual generals ; inevitably there was a regular division of responsibilities . The rank that was subordinate to a top general was a " taxiarchos " or " taxiarhos " , something akin to the modern brigadier . In Sparta , however , the title was polemarchos . Below this was the " syntagmatarchis " , which can be translated as " leader of a regiment " ( " syntagma " ) and was therefore like a modern colonel . Below him was the " tagmatarches " , a commanding officer of a " tagma " ( near to the modern battalion ) . The rank was roughly equivalent to the " legatus " of a Roman legion . Next was the " lokhagos " , an officer who led an infantry unit called a " lokhos " that consisted of roughly a hundred men , much the same as in a modern company led by a captain . A Greek cavalry ( " hippikon " ) regiment was called a " hipparchia " and was commanded by an epihipparch . The unit was split into two and led by two " hipparchos " or hipparch , but Spartan cavalry was led by a " hipparmostes " . A " hippotoxotès " was a mounted archer . A Greek cavalry company was led by a " tetrarchès " or tetrarch . The rank and file of the military in most of the Greek city states was composed of ordinary citizens . Heavily armed foot soldiers were called " hoplitès " or hoplite s and a " hoplomachos " was a drill or weapons instructor . Once Athens became a naval power , the top generals of the land armies had authority over the naval fleets as well . Under them , each warship was commanded by a " trièrarchos " or trierarch , a word which originally meant " trireme officer " but persisted when other types of vessels came into use . Moreover , as in modern navies , the different tasks associated with running a ship were delegated to different subordinates . Specifically , the " kybernètès " was the helmsman , the " keleustēs " managed the rowing speed , and the " trièraulès " was the flute player who maintained the strike rate for the oarsmen . Following further specialization , the naval strategos was replaced by a " nauarchos " , a sea officer equating to an admiral . With the rise of Macedonia under Philip II of Macedon and Alexander the Great , the Greek military became professional , tactics became more sophisticated and additional levels of ranking developed . Foot soldiers were organized into heavy infantry phalanxes called " phalangites " . These were among the first troops ever to be drilled , and they fought packed in a close rectangular formation , typically eight men deep , with a leader at the head of each column ( or file ) and a secondary leader in the middle so that the back rows could move off to the sides if more frontage was needed . A " tetrarchia " was a unit of four files and a " tetrarchès " or tetrarch was a commander of four files ; a " dilochia " was a double file and a " dilochitès " was a double - file leader ; a lochos was a single file and a lochagos was a file leader ; a " dimoiria " was a half file and a " dimoirites " was a half - file leader . Another name for the half file was a " hèmilochion " with a " hèmilochitès " being a half - file leader . Different types of units , however , were divided differently and therefore their leaders had different titles . For example , under a numbering system by tens , a " dekas " or " dekania " was a unit of ten led by a " dekarchos " , a " hekatontarchia " was a unit of hundred led by a " hekatontarchos " and a " khiliostys " or " khiliarchia " was a unit of a thousand led by a " khiliarchos " . The cavalry , for which Alexander became most famous ( in a military sense ) , grew more varied . There were heavy cavalry and wing cavalry ( " ilè " ) units , the latter commanded by an " ilarchos " . Roman ranks . The use of formalized ranks came into widespread use with the Roman legion s after the reforms by Marius . Comparisons to modern ranks , however , can only be loose because the Roman army ' s command structure was very different from the organizational structure of its modern counterparts , which arose from the medieval mercenary companies , rather than from the writings of Fourth Century Roman writer Vegetius and Caesar ' s commentaries on his conquest of Gaul and the civil war . Military command properly so - called was a political office in Rome . A commander needed to be equipped with imperium , a politico - religious concept . The king of course possessed it ( the " rex sacrorum " was strictly forbidden to have it to avoid a return to the monarchy ) . In the Republic , commanding was confined to consuls or ( seldom ) to praetor , or in cases of necessity a dictator . Proconsuls , after the establishment of the office , would also be used . In Imperial times , each legion was commanded by the emperor , who was technically either consul or proconsul . The commander could appoint a deputy , a so - called legate ( " legatus " ) . The association of " legatus " with " legion " is folk etymology , as the meaning of " legatus " is " proxy " or " envoy " . Legates were typically drawn from the Roman Senate for a three - year term . The political nature of high military command was even reflected here , in that legions were always subordinate to the governor , and only the second and further legions stationed in a province had their own " legatus legionis " . The real commanders and the legates together form what in modern terms is the generality . Immediately beneath the commander ( or his legate ) were six military tribune s ( " tribuni militum " ) , five of whom were young men of equestrian rank and one of whom was a nobleman who was headed for the Senate . The latter is called laticlavian tribune ( " tribunus laticlavius " ) and was second in command . If in modern divisions the deputy commander is a brigadier general , the laticlavian tribune can perhaps be translated with this rank , though he commanded no formation of his own . The other tribunes are called " tribuni angusticlavii " and are equivalent to staff officers in both senses of the term : of ranks major , lieutenant colonel , colonel , and with administrative duties . They did not command a formation of their own . The term " military tribune " is even sometimes translated into English as " colonel " — most notably by the late classicist Robert Graves in his " Claudius " novels and his translation of Suetonius ' " Twelve Caesars " — to avoid confusion with the political " tribunes of the people " ; in addition , they must not either be confused with the " military tribunis with conciliar authority " , who in early Republican times could replace the consuls . The third highest officer of a legion , above the angusticlavian tribunes , was the praefectus castrorum . He too would have colonel rank in modern armies , yet he differed much from the tribunes in that his office was not part of the rather administrative " cursus " , but normally filled by former centurions . ( Modern armies have a similar distinction on a lower scale , i . e . between commissioned and non - commissioned officers . ) The fighting men in the legion were formed into " ranks " , rows of men who fought as a unit . Under Marius ' s new system , legions were divided into ten cohort s ( " cohortes " ) ( roughly equivalent to battalion and immediately subject to the legion ) , each consisting of three manipula , each of them of two " centuries " ( a rather small company in modern terms ) , each consisting of between 60 and 160 men . Each century was led by a centurion ( " centurio " , traditionally translated as captain ) , who was assisted by a number of junior officers , such as an Optio . Centuries were further broken into ten " contubernia " of eight soldiers each . The manipula were commanded by one of their two centurions , the cohorts by one of their three manipulum ' s centurions ; the most senior cohort - commanding centurions was called " primus pilus " . The ranks of centurions in the individual cohorts were , in descending order , " pilus prior " , " pilus posterior " , " princeps prior " , " princeps posterior " , " hastatus prior " , and " hastatus posterior " . Individual soldiers were referred to as soldiers ( " milites " ) or legionaries ( " legionarii " ) . Roman discipline was severe , with all ranks subject to corporal and capital punishment at the commander ' s discretion . For example , if a cohort broke in battle , the typical punishment was " decimation " , in which every tenth soldier , selected by lot , was killed . Decimation was not commonplace as lack of men would reduce combat effectiveness , which would eventually overcome the psychological " benefit " of keeping the troops in - line . Turko - Mongol ranks ( Ancestral Central Asian Tribes ) . There were no ranks in the modern sense of a hierarchy of titles , although the army was organized into a hierarchical command . The organization of the army was based on the decimal system , employed by Oghuz Khagan . The army was built upon a squad of ten ( " aravt " ) led by an appointed chief . Ten of these would then compose a company of a hundred ( " zuut " ) , also led by an appointed chief . The next unit was a regiment of a thousand ( " myangat " ) led by an appointed " noyan " . The largest organic unit was a ten thousand man unit ( " tumen " ) also led by an appointed " noyan " . Persian ranks . The army of ancient Persia consisted of manageable military groupings under the individual commands . Starting at the bottom , a unit of 10 was called a " dathabam " and was led by a " dathapatish " . A unit of 1 , 000 was a " hazarabam " and was commanded by a " hazarapatish " . A unit of 10 , 000 was a " baivarabam " and was commanded by a " baivarapatish " . The Greeks called such masses of troops a " myrias " or " myriad " . Among mounted troops , an " asabam " was a cavalry unit led by an " asapatish " . Historians have discovered the existence of the following ranks in Parthian and Sassanian armies : Medieval ranks . Medieval militaries did not have a unified rank structure ; while the feudal lords were in some ways equivalent to modern officers , they didn ' t have a strict hierarchy — a king was conceived of as first among equals , not a monarch as later or ancient societies understood the concept , and all nobles were theoretically equals ( hence " peers " ) . A nobleman was obligated to bring a set number of troops when asked by his liege - lord , a king or merely a higher - ranked noble who had obtained his service by the gift of land . The troops ' lord retained at least nominal control over them — many medieval military planning sessions involved negotiating each lord ' s role in the coming battle — and each lord was allowed to leave after a predetermined amount of time had passed . High command in medieval armies . The king ’ s army was placed under the command of the High Constable as commander - in - chief . The High Constable had authority over the local constables , commanders of the garrisons of major castles . The High Constable had the help of the Field Marshal , an officer that set up the army ’ s camp . ( Marshals acted as chiefs of logistics and were also employed by royal and noble courts . ) The High Constable derived his authority over the army from his role of head of the Cavalry . Origins of modern ranks . As the Middle Ages came to an end , the rank structure of medieval armies became more formalized . The top officers were known as commissioned officers because their rank came from a royal commission . Army commissions were reserved for the elite — the aristocracy of mainland Europe and the aristocracy and gentry of Great Britain . The basic unit of the medieval army was the company , a band of soldiers assigned ( or raised ) by a vassal lord on behalf of " his lord " ( in later times the king himself ) . The vassal lord in command of the company was a commissioned officer with the rank of captain . Captain was derived from the Late Latin word " capitaneus " ( meaning " head man " or chief ) . The commissioned officer assisting the captain with command of the company was the lieutenant . Lieutenant was derived from the French language ; the " lieu " meaning “ place ” as in a position ; and " tenant " meaning “ holding ” as in “ holding a position ” ; thus a “ lieutenant ” is somebody who holds a position in the absence of his superior . When he was not assisting the captain , the lieutenant commanded a unit called a platoon , particularly a more specialized platoon . The word is derived from the 17th - century French peloton , meaning a small ball or small detachment of men , which came from pelote , a ball . The commissioned officer carrying the ( infantry ) company ’ s flag was the ensign . The word ensign was in fact derived from the Latin word insignia . In cavalry companies the equivalent rank was cornet . In English usage , these ranks were merged into the single rank of second lieutenant in the 19th Century . Not all officers received a commission from the king . Certain specialists were granted a warrant , certifying their expertise as craftsmen . These warrant officers assisted the commissioned officers but ranked above the non - commissioned officers . They received their authority from superior officers rather than the king . The first NCOs were the armed servants ( men - at - arms ) of the aristocracy , assigned to command , organize and train the militia units raised for battle . After years of commanding a squad , an NCO could be promoted to sergeant , the highest NCO rank . While a sergeant might have commanded a squad upon promotion , he usually became a staff officer . While commissioned staff officers assisted their commander with personnel , intelligence , operations and logistics , the sergeant was a jack of all trades , concerning himself with all aspects of administration to maintain the enlisted men serving under his commander . Over time , sergeants were differentiated into many ranks as various levels of sergeants were used by the commanders of various levels of units . A corporal commanded a squad . Squad derived from the Italian word for a “ square ” or “ block ” of soldiers . In fact , corporal was derived from the Italian caporal de squadra ( head of the squad ) . Corporals were assisted by lancepesades . Lancepesades were veteran soldiers ; lancepesade was derived from the Italian " lancia spezzata " meaning broken spear - the broken spear being a metaphor for combat experience , where such an occurrence was likely . The first lancepesades were simply experienced privates ; who either assisted their corporal or performed the duties of a corporal themselves . It was this second function that made armies increasingly regard their lancepesades as a grade of corporal rather than a grade of private . As a result , the rank of lance corporal was derived from combining lancepesade and corporal . As the Middle Ages came to an end , kings increasingly relied on professional soldiers to fill the bottom ranks of their armies instead of militiamen . Each of these professionals began their careers as a private . The private was a man who signed a private contract with the company commander , offering his services in return for pay . The money was raised through taxation ; those yeomen ( smallholding peasants ) who did not fulfill their annual 40 - day militia service paid a tax that funded professional soldiers recruited from the yeomanry . This money was handed to the company commanders from the royal treasury , the company commanders using the money to recruit the troops . Origins of higher ranks . As armies grew larger , composed of multiple companies , one captain was granted general ( overall ) authority over the field armies by the king . ( National armies were the armies of the kings . Field armies were armies raised by the king to enter the battle field in preparation for major battles . ) In French history , " lieutenant du roi " was a title born by the officer sent with military powers to represent the king in certain provinces . A " lieutenant du roi " was sometimes known as a " lieutenant général " to distinguish him from lieutenants subordinate to mere captains . The sergeant acting as staff officer to the captain general was known as the sergeant - major general . This was eventually shortened to major general , while captain general was shortened to simply general . This is the reason a major outranks a lieutenant , but a lieutenant general outranks a major general . As armies grew bigger , heraldry and unit identification remained primarily a matter of the regiment . Brigades headed by brigadier generals were the units invented as a tactical unit , by the Swedish king Gustavus Adolphus the second ( " Gustav II Adolf , " who was killed at the battle of Lützen 1632 ) . It was introduced to overcome the normal army structure , consisting of regiments . The so - called “ brigada ” was a mixed unit , comprising infantry , cavalry and normally artillery too , designated for a special task . The size of such “ brigada ” was a reinforced company up to two regiments . The “ brigada ” was a 17th - century form of the modern “ task force ” . In some armies " brigadier general " has been shortened to " brigadier " . Around the end of the 16th century , companies were grouped into regiments . The officers commissioned to lead these regiments were in fact called colonels ( column officers ) . They were first appointed in Spain by King Ferdinand II of Aragon where they were also known as coronellos ( crown officers ) since they were appointed by the Crown . Thus the English pronunciation of the word colonel . The first colonels were captains granted command of their regiments by commission of the king . The lieutenants of the colonel were the lieutenant colonel s . In the 17th century , the sergeant of the colonel was the sergeant major . These were field officers , third in command of their regiments ( after their colonels and lieutenant colonels ) , with a role similar to the older , army - level sergeants major ( although obviously on a smaller scale ) . The older position became known as sergeant major general to distinguish it . Over time , the sergeant was dropped from both titles since both ranks were used for commissioned officers . This gave rise to the modern ranks of major and major general . The full title of sergeant major fell out of use until the latter part of the 18th century , when it began to be applied to the senior non - commissioned officer of an infantry battalion or cavalry regiment . Regiments were later split into battalions with a lieutenant colonel as a commanding officer and a major as an executive officer . Modern ranks . Modern military services recognize three broad categories of personnel . These are codified in the Geneva Conventions , which distinguish " officers " , " non - commissioned officers " , and " enlisted men " . Apart from conscripted personnel one can distinguish : Commissioned officers . Officers are distinguished from other military members ( or an " officer in training " ) by holding a commission ; they are trained or training as leaders and hold command positions . Officers are further generally separated into four levels : General , flag , and air officers . Officers who typically command units or formation s that are expected to operate independently for extended periods of time ( i . e . , brigade s and larger , or flotilla s or squadrons of ships ) , are referred to variously as general officers ( in armies , marines , and some air forces ) , flag officer s ( in navies and coast guards ) , or air officer s ( in some Commonwealth air forces ) . General - officer ranks typically include ( from the most senior ) general , lieutenant general , major general , and brigadier general , although there are many variations like division general or ( air - , ground - ) force general . Flag - officer ranks , named after the traditional practice of showing the presence of such an officer with a flag on a ship and often land , typically include ( from the most senior ) admiral , vice admiral and rear admiral . In some navies , such as Canada ' s , the rank of commodore is a flag rank . In the United Kingdom and most other Commonwealth air forces , air - officer ranks usually include air chief marshal , air marshal , air vice - marshal and air commodore . For some air forces , however , such as those of Canada , United States and many other air forces , general officer rank titles are used . Brazil and Argentina use a system of general officer ranks based on the term brigadier . In some forces there may be one or more superior ranks to the common examples , above , that are given distinguishing titles , such as field marshal or general of the armies ( many armies ) , fleet admiral ( U . S . Navy ) , marshal of the Royal Air Force , or other national air force . These ranks have often been discontinued , such as in Germany and Canada , or limited to wartime and / or honorific promotion , such as in the United Kingdom and the United States . In various countries , particularly the United States , these may be referred to as " star ranks " for the number of stars worn on some rank insignia : typically one - star for brigadier general or equivalent with the addition of a star for each subsequent rank . In the United States , five stars has been the maximum used in all services ( excluding the Marines and Coast Guard , which have only used four ) . There is also a theoretical six - star rank held by John J . Pershing and to which George Washington was posthumously promoted , referred to as the General of the Armies of the United States . Additionally , see admiral of the Navy for the US Navy ' s six - star equivalent , awarded to Admiral George Dewey and subsequently removed after his death . Some titles are not genuine ranks , but either functions assumed by generals or honorific titles . For instance , in the French Army " général de corps d ' armée " is a function assumed by some " généraux de division " , and " maréchal de France " , which is a distinction denoting the most superior military office , but one that has often neutered the practical command powers of those on whom it is conferred . In the United States Navy , a commodore currently is a senior captain commanding a squadron that is too small for a rear admiral to command , although that name has historically been used as a rank . The title ( not rank ) of commodore can also indicate an officer who is senior to a ship ' s captain ( since only the ship ' s commander is addressed as captain while underway ) . Marine captains are referred to as major to distinguish themselves while shipboard . Field or senior officers . Field officer s , also called " field - grade officers " or " senior officers " , are officers who typically command units that can be expected to operate independently for short periods of time ( i . e . , infantry battalions , cavalry or artillery regiments , warships , air squadrons ) . Field officers also commonly fill staff positions of superior commands . The term " field ( - grade ) officer " is primarily used by armies and marines ; air forces , navies and coast guards generally prefer the term " senior officer . " The two terms are not necessarily synonymous . Typical army and marine field officer ranks include colonel , lieutenant colonel , major and , in the British army , captains holding an adjutant ' s appointment . In many Commonwealth countries the field rank of brigadier is used , although it fills the position held by brigadier general in other countries . Naval and coast guard senior officer ranks include captain and commander . In some countries , the more senior rank of commodore is also included . In others lieutenant - commander s , as equivalents to army and marine majors , are considered senior officers or jerrie cadets . Commonwealth air force senior officer ranks include group captain , wing commander , and squadron leader , where such ranks are still used . Company grade or junior officers . The ranks of junior officers are the three or four lowest ranks of officers . Units under their command are generally not expected to operate independently for any significant length of time . Company grade officers also fill staff roles in some units . In some militaries , however , a captain may act as the permanent commanding officer of an independent company - sized army unit , for example a signal or field engineer squadron , or a field artillery battery . Typical army company officer ranks include captain and various grades of lieutenant . Typical naval and coast guard junior officer ranks include grades of lieutenant commander , lieutenant , lieutenant junior grade , sub - lieutenant and ensign . Commonwealth ( excluding Canada ) air force junior officer ranks usually include flight lieutenant , flying officer , and pilot officer . " The [ U . S . ] commissioned officer corps is divided into 10 pay grades ( O - 1 through O - 10 ) . Officers in pay grades O - 1 through O - 3 are considered company grade officers . In the Army , Marine Corps , and Air Force , these pay grades correspond to the ranks of second lieutenant ( O - 1 ) , first lieutenant ( O - 2 ) , and captain ( O - 3 ) , and in the Navy , ensign , lieutenant junior grade , and lieutenant . Officers in the next three pay grades ( O - 4 through O - 6 ) are considered field grade officers . In the Army , Marine Corps , and Air Force , these pay grades correspond to the ranks of major ( O - 4 ) , lieutenant colonel ( O - 5 ) , and colonel ( O - 6 ) , and in the Navy , lieutenant commander , commander , and captain . The highest four pay grades are reserved for general officers in the Army , Marine Corps , and Air Force , and flag officers in the Navy . The ranks associated with each pay grade are as follows : in the Army , Marine Corps , and Air Force , brigadier general ( O - 7 ) , major general ( O - 8 ) , lieutenant general ( O - 9 ) , and general ( O - 10 ) ; in the Navy , rear admiral - lower half , rear admiral - upper half , vice admiral , and admiral . " Subordinate / student officer . Officers in training in the Canadian Armed Forces are either naval cadet for naval training or officer cadet for army or air force training . In the US and several other western forces , officers in training are referred to as student officers , and carry the rank of cadet ( army and air force ) or midshipman ( navy , and in some countries , marines ) . These officers may be serving at a military academy , or , as common in the United States , as members of a military training unit attached to a civilian college or university , such as an ROTC unit . This is due to a requirement that commissioned officers have at least a four - year degree . The British Army refers to its trainee officers as officer cadets , who hold no authority over other ranks ( except when appointed to carry out a role as part of training ) . Officer cadets are referred to as " Mister " or " Miss " until the completion of the early stages of their training , thereafter non - officers will refer to them as " Sir " or " Ma ' am " . While cadet has always been a rank of limited authority and prestige ( cadets and US Navy midshipmen have no authority over commissioned personnel , warrants , or officers , only subordinate cadets ) , midshipman has historically been a rank with limited leadership responsibility , particularly in the Royal Navy . This tradition was continued by the US Navy after its original adoption of the rank , but now US Navy midshipmen are limited in the same manner as cadets in the other US services . Additionally , US Marine officers in training are also midshipmen , trained and educated alongside their naval counterparts , and wear distinctive insignia to indicate their branch of service . Note : US Coast Guard Academy students are referred to as cadets , while those attending the military branch ' s officer candidate school are officer candidates . In the US an alternative to spending four years as a cadet or midshipmen is for college graduates with a four - year degree to attend officer candidate school , an intensive twelve week training course designed to convert college graduates into military officers . Each service has at least one , and usually several , officer candidate school facilities . Students at these programs are called officer candidate s . Warrant officers . Warrant officer s ( as receiving authority by virtue of a " warrant " ) are a hybrid rank treated slightly differently in each country and / or service . Warrant officers may either be effectively senior non - commissioned officer s or an entirely separate grade between commissioned and non - commissioned officers , usually held by specialist personnel . In the United States , warrant officers are appointed by warrant then commissioned by the President of the United States at the rank of chief warrant officer . Warrant officers range from W01 - CW5 . A warrant officer is not a chief warrant officer until they reach W2 . Enlisted personnel . Enlisted personnel are personnel below commissioned rank and make up the vast majority of military personnel . They are known by different names in different countries , such as other ranks ( ORs ) in the United Kingdom and some Commonwealth countries , and non - commissioned members ( NCMs ) in Canada . Non - commissioned officers . Non - commissioned officer s ( NCOs ) are enlisted personnel , under the command of an officer , granted delegated authority to supervise other military members or assigned significant administrative responsibilities . They are responsible for the care and direct control of junior military members , often functioning in the smaller field units as executive officer s . Even the most senior NCO officially ranks beneath the most junior commissioned officer or warrant officer . However , most senior NCOs have more experience , possibly including combat , than junior officers . In many armies , because junior officers have a great amount of responsibility and authority but little operational experience , they are paired with senior NCO advisers . In some organizations , senior NCOs may have formal responsibility and informal respect beyond that of junior officers , but less than that of warrant officers . Many warrant officers come from the ranks of mid - career NCOs . In some countries warrant ranks replace senior enlisted ranks . NCO ranks typically include a varying number of grades of sergeant and corporal ( air force , army and marines ) , or chief petty officer and petty officer ( navy and coast guard ) . In many navies the term " rate " is used to designate specialty , while " rank " denotes paygrade . In some countries warrant officers come under the non - commissioned officer branch ( senior non - commissioned officiers ) . Other enlisted ranks . Personnel with no command authority usually bear titles such as private , airman / aircraftman , or seaman ( starting with seaman recruit in the United States Navy and Coast Guard ) . In the United States Marine Corps individuals of all ranks regardless of command status may be referred to as " marine " . In some countries and services , personnel in different branches have different titles . These may have a variety of grades , such as private first class , but these usually only reflect variations in pay , not increased authority . These may or may not technically be ranks , depending on the country and / or service . Each rank gives the individual an indication of how long and how well they have served in combat and training . Appointment . Appointment refers to the instrument by virtue of which the person exercises his or her authority . Officers are appointed by a royal commission in most monarchies or a presidential commission in many other countries . In the Commonwealth , warrant officers hold a royal or presidential warrant . In the United States , officers are appointed by the president , with the advice and consent of the United States Senate . Most officers are approved " en bloc " by voice vote , but flag officers are usually required to appear before the Armed Services Committee and answer questions to the satisfaction of its members , prior to a vote on their commission . NCOs are appointed by an instrument of appointment , a written document , often a certificate , usually from the service head . Entry into service is often referred to as enlistment throughout the English - speaking world , even in countries where soldiers do not technically enlist . Sometimes personnel serve in an appointment which is higher than their actual rank . For instance , commodore used to be an appointment of captain in the Royal Navy and lance corporal used to be an appointment of private in the British Army . Types of rank . There are a number of different forms of rank ; from highest to lowest degree , they are : After a war , regular serving members of the military holding war substantive or temporary rank often revert to their former , substantive rank and all others often end their service . However , the holder may be granted permission to permanently " retain " the rank they held when the conflict ended . Size of command . Rank and unit size . To get a sense of the practical meaning of these ranks — and thus to be able to compare them across the different armed services , different nations , and the variations of titles and insignia — an understanding of the relative levels and sizes of each command will be helpful . The ranking and command system used by U . S . Marine ground forces or U . S . Army infantry units can serve as a template for this purpose . It should be remembered that different countries will often use their own systems that do not match the presentation here . Under this system , starting from the bottom and working up , a corporal leads a fireteam consisting of three other individuals . A sergeant leads a squad consisting of three fireteams . As a result , a full squad numbers 13 individuals . Squads usually have numbered designations ( e . g . , 1st Squad ) . Generally , in most armies and marine units , a lieutenant or equivalent rank leads a platoon , which can consist of three or four squads . For example , in U . S . Marine infantry units , rifle platoons usually consist of three rifle squads of 13 men each , with a Navy corpsman , the platoon leader , and a platoon sergeant ( i . e . , a staff sergeant who serves as second - in - command ) . An infantry platoon can number from 42 to 55 individuals , depending on the service . Platoons are usually numbered ( e . g . , 1st Platoon ) or named after their primary function ( e . g . , service platoon ) . A captain or equivalent rank commands a company , usually consisting of four platoons ( three line platoons and one heavy weapons platoon ) . His headquarters can include a first sergeant and as many as seven others . As such , a company can comprise from roughly 175 to 225 individuals . Equivalent units also commanded by captains are batteries ( for field artillery units ) and detachments . In English speaking countries , a company ( or troop in the cavalry , and battery in the artillery ) is usually designated by a letter ( e . g . , " A Company " ) . In non - English speaking countries , they are usually numbered . In most Commonwealth armies a company is commanded by a major , assisted by a captain . A lieutenant colonel or equivalent rank commands a battalion or a squadron , often consisting of four companies , plus the various members of his headquarters . A battalion is around 500 – 1 , 500 men and usually consists of between two and six companies . A colonel or equivalent commands a regiment or group , often consisting of four battalions ( for an Infantry unit ) or five to six air groups ( for a wing ) . Battalions and regiments are usually numbered , either as a separate battalion or as part of a regimental structure ( e . g . , 1 - 501st Infantry in the US Army ) . In these latter , abstractions cease to be helpful and it becomes necessary to turn to an actual unit . The 1st Battalion of the 1st Marine Regiment of the 1st Marine Division of the I Marine Expeditionary Force consists of three infantry companies , one weapons company , and one headquarters and service company . Above that , the 1st Marine Regiment ( also known as " First Marines " ) consists of four such battalions and one headquarters company . Marine Air Control Group 18 of 1st Marine Air Wing of the III Marine Expeditionary Force consists of four squadrons , one battery , and one detachment , a mix of different - sized units under a regimental equivalent - sized unit . The next level has traditionally been a brigade , commanded by a brigadier general , and containing two or more regiments . But this structure is considered obsolete today . At the present time , in the U . S . Army , a brigade is roughly equal to or a little larger than a regiment , consisting of three to seven battalions . Strength typically ranges from 1 , 500 to 3 , 500 personnel . In the U . S . Marines , brigades are only formed for certain missions . In size and nature they are larger and more varied collections of battalions than is common for a regiment , fitting them for their traditional role as the smallest formation able to operate independently on a battlefield without external logistical tactical support . Brigades are usually numbered ( e . g . , 2nd Brigade ) . The level above regiment and brigade is the division , commanded by a major general and consisting of from 10 , 000 to 20 , 000 persons . The 1st Marine Division , for example , is made up of four marine regiments ( of the type described above ) , one assault amphibian battalion , one reconnaissance battalion , two light armored reconnaissance battalions , one combat engineer battalion , one tank battalion , and one headquarters battalion — totalling more than 19 , 000 marines . ( Within the headquarters battalion are one headquarters company , one service company , one military police company , one communications company , and one truck company . ) An equivalent elsewhere within the same marine expeditionary force ( MEF ) might be a MEF logistics group ( MLG ) - which is not a regimental - sized unit ( as the word " group " implies ) , but rather a large support unit consisting of several battalions of support personnel . Divisions are normally numbered , but can be named after a function or personage . Considering such a variety of units , the command sizes for any given rank will vary widely . Not all units are as troop intensive as infantry forces need to be . Tank and artillery crews , for example , involve far fewer personnel . Numbers also differ for non - combat units such as quartermaster s , cooks , and hospital staff . Beyond this , in any real situation , not all units will be at full strength and there will be various attachments and detachments of assorted specialists woven throughout the system . The 1st Marine Division is part of the I Marine Expeditionary Force , which also includes the 3rd Marine Air Wing , 1st Marine Logistics Group , 1st Marine Expeditionary Brigade ( as required ) , three marine expeditionary units ( featuring helicopter groups ) , and a battalion - sized marine air ground task force . In the U . S . Marine Corps there are three marine expeditionary forces . In the U . S . Army , the level above division is called a corps instead of an expeditionary force . It is commanded by a lieutenant general . In many armies , a corps numbers around 60 , 000 , usually divided into three divisions . Corps ( and similar organizations ) are normally designated with roman numerals and their nationality when operating in a combined ( international ) force , e . g . V ( US ) Corps , VIII ( ROK ) Corps , II MEF , I Canadian Corps . During World War II , due to the large scale of combat , multiple corps were combined into armies commanded in theory by a general ( four stars ) , but often by a lieutenant general ( three stars ) , and comprising as many as 240 , 000 troops . Armies are numbered by spelled - out numerals or functional titles , using their nationality in " combined " forces ( e . g . , Eighth US Army , Third ROK Army , British Army of the Rhine ) . These were in their turn formed into army group s , these being the largest field organization handled by a single commander in modern warfare . Army groups included between 400 , 000 and 1 , 500 , 000 troops . Army groups received Arabic numeral designations and national designations when combined . These examples illustrate a standard that holds true all over the world and throughout military history , namely that higher rank generally implies command of larger units in a nested system of ranks and commands . The specific size of a command for any given rank will , however , depend on the task the unit performs , the nature of weapons used , and the strategies of warfare .