Military ranks are a system of hierarchical relationships within armed forces, police, intelligence agencies and other institutions organized along military lines. Responsibility for personnel, equipment and missions grows with each advancement. The military rank system defines dominance, authority and responsibility within 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 is an important component for organized collective action.
Uniforms denote the bearer's rank by particular insignia affixed to the uniforms of a number of countries. Ranking systems have been known for most of military history to be advantageous for military operations, in particular with regard to logistics, command, and coordination. As time went on and military operations became larger and more complex, more ranks were created and the systems of ranking became more complex.
Rank is not only used to designate leadership, but to establish pay-grade as well. As rank increases, pay-grade follows, but so does the amount of responsibility.
In modern armed forces, the use of ranks is almost universal. Communist states have, on several occasions, abolished the use of ranks (e.g., the Soviet Red Army 1918–1935, the Chinese People's Liberation Army 1965–1988, and the Albanian People's Army 1966–1991), but they have had to re-establish them after encountering operational difficulties in command and control.
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 means "army leader" and is usually translated as "general". Originally these generals worked together with the old polemarchos ("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.
As an elected official a Strategos is by definition not a military rank. Strategos is a Political Rank in a Hierarchical Position above the military, politically similar in nature to a modern-day Sheriff or Police Commissioner. This is completely different from a modern day Commissioned Military General who never stands for election at any point in their careers. Historically it is unclear whether there was any badge of office granted to a Strategos though given current customs one should suspect that there was such a badge of office.
The confusion regarding the "Ranking" of Strategos surely stems from the modern custom of granting Police Commissioners and Sheriff's, both Political Ranks, a badge-of-office that happens to be in the shape of what is commonly understood to be a very high rank within the traditional military hierarchy. This "rank-shaped" badge-of-office a formal representation of Public Civilian (political) authority over military matters.
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 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 hoplites 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 one 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.
The use of formalized ranks came into widespread use with the Roman legions 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 early modern, Thirty Years' War 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 who 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 praetors, or in cases of necessity a dictator. Proconsuls, after the establishment of the office, were used. In imperial times, each legion was commanded by the emperor, who was technically either consul or proconsul.