The Central Galactic Union Army is the land component of the Union military, and is the largest branch of the uniformed services. The Army is responsible for conducting most land military operations and establishing "land dominance" at a strategic, operational, and tactical level. Its roots lay with the oldest armed services in human history, and traces its lineage to ancient Earth armies extending into Bronze Age antiquity. Its strongest traditions are tied to the Terran Imperial Army, which gathered most of its structure, system, and history from the militaries of North America, Western Europe, and China.
As a uniformed military service, the Union Army is part of the Department of the Army, which is one of the four military departments of the Ministry of War. The Union Army is headed by an appointed civil servant, the Secretary of the Army, and by a chief military officer, the Chief of Staff of the Army who is also a member of the Joint Military Staff. The reported manpower strength of the Army included around 1.4 trillion active-duty expeditionary soldiers, 1.6 trillion active defence soldiers, and 6.5 trillion reservists. The combined force of the Army stands at around 10 trillion personnel, constituting a third of all servicemembers.
The Union Army has its roots in the military traditions of the member nations of the Interstellar Treaty Organization, especially that of the Terran Empire. The structure of the Terran Imperial Army served as the basis for operational and tactical organisation. The Imperial Army was under the administrative oversight of the Army Office within the Imperial Ministry of War. This followed from Earth traditions in which the military was governed by civilian authorities. The largest empires of the ISTO, including the Empire of Orion, the Empire of Sagittarius, and the Federation of Cygnus, operated their armies under similar principles. A few states, most notably the Despotate of Perseus, had an independent General Staff managing their military with the only civilian oversight being the monarch directly.
The Terran Imperial Army largely drew its traditions from the ancient Earth armies of Britain, Russia, Western Europe, Germany, China, Japan, and the United States. These armies had formed, at various stages, the Allied forces of the 20th century World Wars, the North Atlantic Treaty Organization, the United Nations Security Council, and the United Nations Armed Forces. These cultural traditions informed to a great extent the armies of the allied forces in the Interstellar Treaty Organization.
The Allied Command Staff of the ISTO had operational control over the joint forces of the member states in times of jointly-conducted war. The Great War saw the greatest depth of coordination between the participating armies. The Galactic Confederation, replacing the ISTO in November 3270, vested the conduct of common military policy in the War Committee, which devolved its powers to the respective War ministries of the member states. As a practical matter, the Terran Imperial military managed most the Confederate armed forces as it was the largest military in the confederation.
After the dissolution of the member states in March 3275, the Confederate armed forces were in a state of limbo. This was resolved with the transition to the Republic in April. The provisional Congress of the Republic made for a temporary War Office to manage the military forces. The Ministry of War, Department of the Army, and the Army proper were formed on 2 February 3276 with the Defence Authorization Act passed by the first Central Galactic Congress.
The majority of Army forces were organised as defensive troops to garrison the many worlds administered by the Republic. After the war, many soldiers in the various former national armies were deactivated and discharged. The public perception was that, having completed the conflict and won the Final Victory, the Army could be shrunk to a size of strict necessity. A core group of soldiers were retained, largely from the Terran provinces, to form an expeditionary force under the Army Forces Command to combat colonial and regionalist insurrections. Many soldiers from across the Galaxy re-enlisted to serve in the active defence forces. However, the revolt in the Outer Rim and the Occupied Territories in 3279 sparked the re-evaluation of military policy. The Army Forces Command was vastly expanded in the 3280 budget to double its previous size. Activation of reservists and greatly expanded recruitment programs swelled the Army. The Army was deployed in ground-fighting operations throughout the galaxy against the Alien Remnant forces, colonial insurrectionists, pirates, and gangs between 3279 and 3288.
The course of the Army changed in April 3288. The ambush of Republic exploratory spacecraft by armed forces of the Zaaroft Imperium instigated the Magellanic War. The Special High Command for the Magellanic Clouds was formed to coordinate all joint operations in that theatre of operations. This command was held by the High Commander for Joint Forces in a "dual hat" role to manage the expeditionary forces. The Army provided a significant amount of expeditionary troops for this command. The 3289 budget doubled again the Army Forces Command in order to provide a constant flow of troops.
The Union Army is headed administratively by the Secretary of the Army, who has civilian oversight over the Army General Staff and the Union Army. The General Staff is headed professionally by the Chief of Staff of the Army, an active-duty general officer who is the chief adviser on Army matters and chief advocate on the Army's professional, technological, and operational development. The Chief of Staff is statutorily an officer of the rank of Supreme Marshal. The Chief of Staff also serves on the Joint Military Staff, an agency of the Ministry of War composed of the service chiefs and joint high commanders who provide, under the guidance of the Chairperson of the Joint Staff, advice on military matters. The Department of the Army is headquartered at The Pentagon in Arlington, Virginia. The Army General Staff and its operational components are headquartered at the Bendlerblock building in Berlin, Brandenburg.
The Army is divided operationally into Major Commands. These commands are held by Army Major Commanders, statutorily officers of the rank of Chief Marshal (O-14). They serve as the land forces deputies to the Joint High Command and Joint Combatant Command staffs. These officers also serve as the direct commanders of their subordinate units under the oversight and orders of their commanders.
Four Major Commands are based around particular tasks or purposes. Army Forces Command is tasked with the training and operation of expeditionary troops and its commander is the ground forces deputy to the Joint Forces Command staff. It is the largest single Major Command and controls the nearly 1 trillion active-duty soldiers who are assigned to various expeditionary forces, providing a constant flow of trained and ready soldiers to military expeditions. Forces Command is of great importance to the current Magellanic War. Army Reserve Command, Army Special Operations Command, Army Strategic Command, Army Medical Command, and Army Logistical Command are the Army deputational commands who are tasked with training and provision of Army forces for their respective Joint High Commands.
In addition to these, there is an Army Major Commander for each of the Sector-level geographical Combatant Commands with operational oversight of the Army components to the joint commands. Each of these control a different amount of personnel, with the "operational building block" being an Army Group. Such groups are tasked with the defence of an entire star system; the average Combatant Command possesses at least a hundred active Army Groups, and correspond to one of the Sector-level governing units of the Union. Some have more, if they are deemed particularly strategically significant. The geographical Joint Combatant Commands operate nearly 10,000 active-duty Army Groups as defensive forces stationed on-world. A few additional Army Commands handle special areas of responsibility, such as the ground defence of the capital city held by the Capital District Command, the Army Educational Command, the Test and Evaluation Command, the Army Corps of Engineers, and the Army Corps of Chaplains. These commands are of less broad responsibility than the other Major Commands and typically are commanded by officers less than Marshal rank.
The operational basis of the Army, whether in expeditionary or defensive forces, is the Army Group. An Army Group is a self-sufficient combined-arms force commanded by a General Field Marshal (O-13) and consists of between six and ten Field Armies, each commanded by a Captain General (O-12). A Field Army consists of between three and eight Tactical Armies, themselves commanded by a Colonel General (O-11) or a General (O-10). A Tactical Army is the smallest combat unit capable of independent planetary operations; as demonstrated in the Great War, these units of around half a million to one million soldiers can deploy onto a planet and perform encirclement and strike operations to suppress planetary defences and seize strategic objectives.
Tactical Armies are composed of several Corps, commanded by a Lieutenant General (O-9). Corps are composed of a variable number of Divisions, commanded usually by a Major General (O-8) and consisting of between ten and twenty thousand soldiers. Divisions are considered the main "tactical unit of operation" and are the smallest combined-arms operational unit employed by the Army in theatres of operation. A Division is usually based around a particular set of operational specialities, and is composed of a number of modular, tactical units of a more specialised nature.
Army tactical units are of Divisional scale and smaller. Divisions are composed of a varying number of specialised Brigades, the smallest self-sufficient tactical unit. Usually a Division has three to four manoeuvre Brigades, an Aviation Brigades, and a Support Brigade, as well as a command and support headquarters unit, the Divisional Special Troops Battalion. Brigades are commanded ideally by a Brigadier General (O-7), but sometimes are commanded by a Colonel (O-6). Brigades are usually composed of a Brigade Headquarters Company as a command and support unit, and around six to eight battalions.
Regiments are largely historical and ceremonial formation composed of three to four battalions, akin to a small brigade. Regiments are not usually used in field duty as a tactical unit of operation, and have not been employed as such since the 2600s. Rather, its constituent battalions are rotated into brigades for field duty. However, some reserve brigades are styled as Regiments for historical purposes. Regiments are typically commanded by a Colonel.
Battalions are composed of between two and six Companies, and are commanded by a Lieutenant Colonel (O-5) or a Major (O-4) along with a command staff. Battalions and Companies are usually very specialised; artillery companies are referred to as a Battery and cavalry companies are referred to as a Troop. Each Company is headed by a company officer, usually a Captain though a First Lieutenant and a Major may be found in command, and is composed of around 250 soldiers, divided into four to five platoons.
A Platoon is a fixed unit of fifty soldiers, based around five squads of nine soldiers plus a platoon headquarters team. The Platoon is the smallest tactical unit led by a commissioned officer, usually a Lieutenant. Squads are small tactical units of manoeuvre, commanded by a non-commissioned officer of Sergeant or Staff Sergeant rank. Squads can be subdivided into fireteams of three soldiers, usually two of them being led by a Corporal or Lance Corporal, and one by the squad leader themselves.
In the field, tactical units are often detached from their formal units of organisation and employed in "battle groups" or "task forces" based around a balance of specialities and armaments. The strategic doctrine in Army expeditionary and defensive forces differ widely, as both have very different responsibilities. However, operationally and tactically, they are similar in that they are based on mission-based tactics and fast-moving encirclements and pincer manoeuvres. The experiences of the Great War have greatly affected the planning and doctrine of the Army.
A significant proportion of active-duty and reserve soldiers in the Army are volunteers, enlisting or commissioning into the Army as a career. Recruitment for such volunteers is done through the numerous recruiting stations on member worlds of the Republic, and through mass media. Visual arts, performing arts, radio and television broadcast, telephone calls, social media presence, and email lists are all used as a medium for recruitment messages. Incentives for voluntary enlistment include preferential placement into branch and arm of service and greater career potential and opportunity for advancement in comparison to conscription, as well as the ordinary benefits of military personnel: above-average pay, comprehensive healthcare, and government-subsidized housing, nutrition, insurance, and higher-level education.
All human citizens aged 18 to 25 are eligible for conscription into National Service, which includes military service. Not all citizens are automatically inducted into service; induction is determined by lottery selection. Induction is deferred until the end of secondary school for those who come of age while attending secondary school. Eligible citizens are required to take an aptitude test, physical examination, and a background examination upon induction to determine qualification for enlistment into the Armed Forces. Army service constitutes the majority of conscription placements. The majority of conscripted soldiers are assigned to reserve units, though some are assigned to active duty.
Upon induction, Army soldiers are sent to a Military Training Depot on a "hub world". Typically, each nebular cluster has one depot world. Each depot has a complex of training facilities for all branches and arms of service. Army training starts with Basic Training, consisting of a 60-day course which crafts discipline as well as physical and mental adjustment to military service. It is followed by Advanced Training, the duration of which differs based on arm of service or occupational specialty. For instance, Infantry School consists of a four-week course in basic and advanced techniques for close combat, followed by a two-week Harsh Environment Training course. Advanced Training may last between four weeks to eighteen months, depending on the training course.
The Army utilises a wide array of personal or individual weapons to provide light firepower at short ranges. The experiences in various past wars of the Terran Empire and its allies, but most especially of the Great War, have demonstrated the need for both short-ranged, intermediate-calibre weapons and for longer-ranged, full rifle-calibre weapons available for different tactical situations. The most common weapons in use are the M-150 Battle Rifle, the 7.92x57mm service rifle; and the AR-78 Assault Rifle, a closer-ranged, compact rifle chambered in 7.92x33mm. Many defensive units are equipped with older stock weaponry from the Great War era, and have yet to receive the newest infantry weapons, which are stocked first with the expeditionary troops. Such weapons include the AR-38 Service Rifle (chambered in 7.92x57mm), the FG-101 Para Rifle (chambered in 7.92x33mm), and VG-61 Defense Carbine (chambered in 7.92x33mm). The standard sidearm of all Army units is the P64A Service Pistol, which has been utilised since the 3260s. Previously the standard sidearm was the Colt-Walther Navy "Moderne" Revolver, a ruggedly reliable but technologically antique and unsophisticated weapon.
Many units make use of a variety of other, more specialised weapons as a supplement for standard arms or in replacement due to their particular uses. These include such "commando" weapons for special operations units, like the K-3 Commando Rifle (chambered in 6x43mm), the caseless HG-8 Helix Rifle and XR-31 Rifle, and the A-31 Flechette Rifle. Suppressive fire is often provided through the MG-131 Squad Automatic Weapon at the team- or squad-level. Indirect fire usually comes from one of a variety of standard grenade launchers, including the drum-fed, revolver-style L-19 Grenade Launcher (firing 40x46mm grenade rounds), the magazine-fed, semi-automatic GrW-86 Individual Counter-Defilade Weapon (firing smaller 25x40mm grenade rounds), the breech-loading GW-2 Hand Mortar (despite the name, firing 50x66mm grenades), or the under-barrel GG-11 Rifle Grenade Module (firing 40x46mm grenades) ordinarily affixed to service rifles but which can be detached and used on its own. The semi-automatic M-23B Combat Shotgun and the M77 Automatic Shotgun are used for door-breaching and close quarters combat. Squad-level marksmen make use of the SR-38 Designated Marksmen Rifle (a modified and scoped AR-38 rifle) and the M991 Sniper Weapon System (a modified M-150 rifle) for long-range fire support, while sniper specialists at platoon-level teams train for use with the M991E and the bolt-action PSG Precision Rifle. Hand grenades are used, including the Model 1 Fragmentation Grenade, the Model 12B Beryl Grenade, the Model 4 Incendiary Grenade, the Model 84 Stun Grenade, and the Model 20 Smoke Grenade.
Vehicle crews typically make use of smaller primary firearms than other soldiers, called "personal defence weapons". These include submachine guns, machine pistols, and some carbines. The most common of such weapons used are the top-loading, "bullpup" MPK-81 Personal Defence Weapon (chambered in 5x30mm), the old but reliable Mk.9K Submachine Gun (chambered in 9x19mm), the FMP-5 Folding Machine Pistol (chambered in 9x19mm), the CS-5 Compact Submachine Gun (chambered in 10x20mm Navy), and MPK-1 Combat Machine Pistol (chambered in 6.5x20mm).