Military organization

• 1. Introduction

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  Military organization begins with a deceptively simple question: when you need an army, how do you build one? The Roman Army answered that question by organizing its soldiers into legions, each comprising around 5,000 soldiers and led by a legate. Those legions were then divided into centuries, each under the command of a centurion. That Roman template, with its hierarchical layers of command flowing down from a single authority, set the pattern that armed forces around the world still follow today.

  But the structure of a modern military is far more elaborate than any Roman could have imagined. Governments oversee ministries of defence. Those ministries command branches. Branches command formations. Formations command units. And somewhere inside all of that machinery, the question of what to call each layer, and how many troops it holds, and who leads it, produces a labyrinth of terminology that shifts from country to country, service to service, and war to war.

  How does a division differ from a brigade? What is a task force, and why does it exist outside the regular hierarchy? Why does the word "squadron" mean completely different things in a navy, an air force, and a cavalry regiment? Those are the puzzles that the story of military organization is built to answer.

• 2. The Roman Foundation

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  Formalized ranks in a hierarchical military structure came into widespread use with the Roman Army. The legion was the defining unit: around 5,000 soldiers, commanded by a legate. Below him, centurions commanded the centuries that were the legion's working parts. This was not merely an administrative convenience. The hierarchy made it possible to coordinate large bodies of men across great distances and changing conditions, translating a general's intent into the movement of individual soldiers.

  The influence of that model persisted long after Rome itself faded. Many of the organizational concepts used by European armies, and subsequently by armies worldwide, trace their logic back to the same principle: one officer, a defined span of control, and a clear chain of responsibility running upward. The Corps, for instance, was first introduced in France around 1805 by Napoleon as a more flexible tactical grouping of two or more divisions during the Napoleonic Wars. Napoleon did not invent the concept of hierarchy, but he demonstrated how it could be restructured to create speed and adaptability on a battlefield that older, more rigid formations struggled to handle.

• 3. Commands, Formations, and Units

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  At least in European and North American militaries, the building blocks of an armed force are typically described as commands, formations, and units. Each word carries a specific meaning that matters in practice.

  A command is a collection of units and formations under a single officer. During World War II, the word took on an additional meaning in the United States Army, where it was also applied to a type of battlegroup. In general, a command is an administrative and executive strategic headquarters that reports to the national government or the national military headquarters. Nations sometimes organize each of their services into its own command; in the Belgian Army, for example, those components are called the Land Component, Air Component, Naval Component, and Medical Component.

  The U.S. Department of Defense defines a formation as "two or more aircraft, ships, or units proceeding together under a commander." The Great Soviet Encyclopedia offered a different emphasis, describing formations as military organisations built from different speciality arms and services to create a balanced, combined combat force. Divisions, brigades, battalions, and wings all qualify as formations. The word can also refer to a tactical arrangement of troops in the field, such as the testudo formation or the panzerkeil.

  A unit, by contrast, is homogeneous. Its service personnel come predominantly from a single arm or branch of service, and its administrative and command functions are self-contained. Commonwealth practice reserves the word "formation" for organizations at the division and brigade level and higher; battalions are called units, and their constituent companies or platoons are sub-units. In the United States, the terms unit and formation are frequently used interchangeably, which produces some of the confusion visitors to American military documents often encounter.

• 4. The Army Ladder

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  The army hierarchy runs from the fireteam at the bottom, with two to four soldiers, up through squad, section, platoon, company, battalion, regiment, brigade, division, corps, field army, army group, and finally the combatant command or theater, which can comprise between one million and ten million personnel. Each rung carries its own commander rank and its own span of subordinate units.

  In NATO forces, rungs are sometimes skipped. Forces typically jump directly from battalion to brigade, for instance. The naming conventions also diverge in ways that genuinely confuse outsiders. A British or Canadian armored regiment is equivalent to a battalion. Its internal divisions are called squadrons, which correspond to companies, and troops, which correspond to platoons. An American cavalry squadron is battalion-sized; its subunits are troops at the company level and platoons below that. In the French system, used by many African countries, the company is divided into sections, which are composed of three combat groups of seven soldiers each, plus a vehicle crew group and a headquarters element that includes two snipers.

  The role of support elements has also migrated down the hierarchy over time. Divisions were traditionally the level at which field artillery, hospital units, logistics, and maintenance were added. Since World War II, many brigades have acquired those support units. Since the 1980s, regiments have been receiving them as well. A regiment with such support elements is called a regimental combat team in U.S. military parlance, or a battlegroup in the United Kingdom and other forces.

  The Red Army of World War II presents a striking case study in how the labels can mislead. In the early war years, many Red Army units were severely understrength, and a division in that force was roughly the size of most nations' regiments or brigades. At the top of the hierarchy, what other nations called an army group the Red Army called a front. At the other extreme, German Wehrmacht army groups on the Eastern Front, Army Group Centre among them, exceeded the standard numbers considerably and were more comparable in scale to the Soviet Strategic Directions.

• 5. Naval Structure and Its Flexibility

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  Naval organization at the flotilla level and higher is less rigidly followed than army hierarchy, because ships operate in groups that may change size and composition at very short notice. Navies are generally organized into groupings for specific strategic purposes, and those groupings appear and disappear as conditions demand. This sets naval organization sharply apart from the army model, where units remain static in composition over extended periods.

  At the broadest scale, a combatant command or full navy encompasses all vessels under an admiral of the fleet, fleet admiral, grand admiral, or admiral. Below that, a fleet covers all vessels in an ocean or general region. Further down the ladder come battle fleets, task forces, carrier strike groups, divisions, flotillas, squadrons, and finally the single vessel, which may be commanded by a captain, commander, lieutenant commander, or lieutenant, depending on its size. The five-star ranks of admiral of the fleet and fleet admiral have largely been out of regular use since the 1990s, kept alive mainly for ceremonial or honorary appointments.

  The hierarchy extends inside a single ship as well. The ship's complement is organized into three or four departments, each of which has a number of divisions, followed by work centers. Historically, navies were far more rigid than they are today; a vessel could not move from one unit to another without written permission. The modern U.S. Navy is primarily structured around the carrier strike group and the expeditionary strike group.

• 6. Air Forces and the Squadron Problem

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  Air force organizational structures vary more sharply between nations than army or naval structures do. The United States Air Force and the Royal Air Force are divided into commands, groups, and squadrons. The Soviet Air Force used an army-style organizational structure. The modern Royal Canadian Air Force uses an air division as the formation between wings and the overall air command; its wings, like the RAF's, consist of squadrons.

  The squadron is the unit that most vividly illustrates how a single word can fracture into multiple meanings across different services. In most navies, a squadron is a formation of several ships. In most air forces, it is a unit. In the U.S. Army, a squadron is a battalion-sized cavalry unit. In Commonwealth armies, a squadron is a company-sized sub-unit. Four services, four different scales, one word.

  A wing or group in the air force comprises roughly 1,000 to 5,000 personnel and 48 to 200 aircraft, commanded by a brigadier general in the U.S. or an air vice marshal or air commodore in the RAF. A squadron sits below that, at 100 to 300 personnel and 7 to 16 aircraft, commanded by a lieutenant colonel or major in the U.S., or a wing commander or squadron leader in the RAF. Below the squadron, a flight holds 20 to 100 personnel and 4 to 6 aircraft.

• 7. Task Forces and Temporary Groupings

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  A task force is a unit or formation created as a temporary grouping for a specific operational purpose. The concept of mission-related organization has roots stretching back to the early 17th century in Europe, when fighting forces began to be grouped outside the standard administrative hierarchy for particular objectives.

  During the Second World War, several distinct versions of this idea emerged simultaneously. The German Kampfgruppe and the U.S. Combat Team operated on the army side. The U.S. Navy developed its own Task Force model. The British and Commonwealth armies relied on the battlegroup as the standard grouping of companies during both the Second World War and the Cold War. The Soviet Operational manoeuvre group served a similar function during the Cold War.

  NATO added its own layer of terminology to distinguish between different combinations. A Joint Task Force, known as a JTF, is a temporary grouping that includes elements from more than one armed service. A Combined Task Force, or CTF, is a temporary grouping that includes elements from more than one nation. A Combined Joint Task Force, CJTF, combines both: elements from more than one armed service and more than one nation. The table of organization and equipment, a document published by the U.S. Army Force Management Support Agency, prescribes the permanent structure, manning, and equipment of units from divisional size downward, providing the stable baseline against which these temporary groupings are assembled and then dissolved.