Inner Sphere Military Structure
Every military unit in the BattleTech universe, whether regular or mercenary, is divided into sub-units to facilitate organization, deployment, and combat operations. Mercenary units are extremely varied; some, like Carlyle's Commandos were a single lance while others, like Eridani Light Horse, Wolf's Dragoons, and the 12th Star Guards, consist of several regiments.
There is some common terminology for these organizational structures, and there are also differences between BattleMech, infantry, and aerospace fighter units. There are also disparities between the five Great Houses and especially between entities in the Periphery. Clan military structure and that of ComStar and the Word of Blake's military forces are substantially different from any Inner Sphere unit organizations.
Each unit is organized differently in practice, but many follow a basic organizational structure that enables them to integrate with other units easily and effectively.
The lance is the smallest organizational unit, equivalent to an infantry platoon. A 'Mech lance consists of four separate BattleMechs (although occasionally a "light lance" consists of only three 'Mechs) and are categorized based upon the average weight of the 'Mechs that comprise it (Light, Medium, Heavy, Assault). A lance commander is usually either a non-commissioned officer (NCO) or a low grade officer (lieutenant or equivalent). Lance commanders are directly engaged in combat operations and are responsible for the 'Mechs under their command.
A standard lance consists of one light, one medium, and two heavy BattleMechs.
In addition to four 'Mech pilots, there are normally four to six additional support personnel, making a lance roughly ten individuals.
Many smaller mercenary commands are typically one to two lances and their support staff; exact organization can depend on what a given command has available to it.
After learning of the Novas used by the Clans, the Capellan Confederation Armed Forces began to experiment with mixing unit types. Their first successful experiment created an augmented 'Mech lance that combined four BattleMechs with two combat vehicles. This became the "standard" augmented 'Mech lance. A "secondary" augmented 'Mech lance was created by combining four BattleMechs with two squads of battle armored infantry. The CCAF then turned their attention to armor lances. The "standard" augmented armor lance combines four combat vehicles with two BattleMechs; The "secondary" augmented armor lance combines four combat vehicles with four squads of battle armor-equipped infantry.
A Company consists of three lances and normally some auxiliary Lances, scouts, armor, or artillery. A company commander is normally either a major or captain (or equivalent). The company commander is usually the leader of the command lance of a company and is directly involved in combat operations. Companies are more self-sufficient than lances and consist of the combat troops and support personnel, including medical, technical, and planetary transport vehicles (DropShips).
In addition to twelve 'Mech pilots and the eighteen support personnel, there are usually additional support or specialist personnel, making a company roughly sixty individuals. Three companies comprise a battalion. Mercenary units commonly do not exceed the size of a company.
This formation is used only by the CCAF. It has the twelve combat units of a typical company, but these are organized into two Augmented Lances of any type.
Company Task ForceEdit
A combined arms formation based around a parent company that is made up of between eighteen and twenty-four combat units. 
A battalion consists of three companies and is a large organization. It is normally composed of at least thirty-six 'Mechs plus aerospace, artillery, reconnaissance, medical, and numerous other support staff and personnel. Overall, a battalion may consist of over two or three hundred individuals. Battalions are commanded by either a lieutenant colonel (or equivalent). Battalion commanders normally do not participate directly in combat operations, but personal preference dictates this. Most battalion commanders direct operations rather than engage enemy forces.
Battalions are extremely self-sufficient and capable fighting forces. They are capable of traveling over the surface of a planet and deploying significant fire power anywhere within a short period of time. Many mercenary units never achieve a size comparable to that of a battalion.
This formation is used by the CCAF and consisted of four companies of two Augmented Lances each and a command lance.
The most commonly used augmented lance in these battalions consisted of four 'Mechs and a pair of conventional tanks. The four companies provided thirty-two 'Mechs and the command lance added four more. This gave the Augmented Battalion the same firepower as a standard battalion, but included sixteen armored vehicles for additional fire support.
A variant battalion consisting of four companies, and may also have a Command Lance (48 BattleMechs/aerospace fighters). This organizational structure came about when the Inner Sphere militaries re-purposed the air lance that would support each company.
Regiments are very large organizations and the great houses normally organize their regular units into regiments; these are the largest formations in common use. This is traditionally the lowest level of organization that a house's high command will direct (outside of mercenary units). Regiments are commanded by colonels or their equivalent. Regimental commanders rarely engage in combat operations personally; the ability to organize a regimental-sized group is usually not possible on the field of battle. The size of the unit in personnel is not just based upon the combat forces, but it also includes the technical, transportation, scout, and other support personnel and materiel. Regiments are self-sufficient units and usually have their own dedicated DropShips and possibly even JumpShip.
Regiments consist of three to five battalions, commanded by a Colonel or General, for a total of one hundred and eight to one hundred and eighty 'Mechs or combat vehicles. Additional support battalions such as infantry are often attached to the regiment as well.
In 3081 the Capellan Confederation began organizing Augmented Regiments that expanded the use of their Augmented Lance and Augmented Company organization. Each 'Mech regiment of the CCAF was reorganized to include at least one Augmented Battalion.
Though rare, Augmented Regiments composed entirely of conventional vehicles and infantry also exist.
The Average Regimental Composition scheme, also known as "Forward ARC", was commonly used by the Draconis Combine. Front-line 'Mech regiments were typically assigned an armor battalion, an infantry regiment, and an aerospace wing, all of whom answered to the 'Mech regiment's commanding officer.
Regimental Combat TeamEdit
First developed by the Star League Defense Force, a Regimental Combat Team was originally composed of four combat regiments and a support and transport element. The most experienced regimental commander was put in charge of the RCT, and the four combat elements trained together to improve unit cohesion. These RCTs tended to be permanently assigned to a location in order to better understand and exploit the local terrain. A surviving example of the SLDF's RCT concept is the Eridani Light Horse.
The Federated Suns would develop their own Regimental Combat Teams thanks to First Prince Melissa Davion after she came to power in 2876. The Armed Forces of the Federated Suns' version of an RCT is a large multi-regiment formation that consists of a regiment of BattleMechs, three regiments of combat vehicles, five regiments of infantry, two aerospace fighter wings, and a battalion of artillery. Most will also include one or more battalions of engineers and may be assigned other units as needed, such as Special Forces or marines.
Unlike the task forces that had been used previously, these regiments are permanently assigned to work together. These RCTs are usually named for the BattleMech regiment, though the individual components retain their own names. Composition varied between different RCTs, but typically two of the armor regiments were medium and the third heavy, while two of the infantry regiments were foot infantry, two were mechanized and the fifth jump infantry. Following the Fourth Succession War and formation of the Federated Commonwealth, RCTs began converting their foot regiments to mechanized, although this was only partially complete by the time of the Clan Invasion. Afterwards, many began converting one of the infantry regiments into an armored infantry battalion. Many RCTs also began to include at least a company of battle armor suits, with some assigned an entire battalion of them. After the sundering of the Federated Commonwealth, the Lyran Alliance also adopted the RCT model, although given chronic shortages and less emphasis on aerospace forces many lacked assigned fighter wings.
Light Combat TeamEdit
After the widespread destruction of the Jihad, the AFFS shifted over to a defensive mindset. Though it still had several RCTs on the rolls, the majority of the units were rebuilt as Light Combat Teams. A smaller version of the AFFS' traditional RCT, the LCT was a reinforced battalion of 'Mechs (typically three companies plus a two-to-three lance command company), two to three battalions of heavy and assault armor, an equal number of cavalry battalions, and an artillery company. Additionally the LCT includes a regimental-size Battle Armor formation (though in most cases the size is much smaller) and VTOL assets to provide transportation for the Battle Armor as well as reconnaissance for the LCT. The large conventional infantry forces of the RCT have been reduced to those troops needed to provide engineering, security, and other support roles.
Though no longer in common use, there are several larger formations that military planners accept as common terms.
A Brigade is a military formation typically consisting of 3 or more regiments, usually of similar weight classes and capabilities. This formation was used extensively by the SLDF, but is no longer used by most Inner Sphere militaries. Brigades were usually commanded by a Lieutenant General and limited to being no more than five regiments in size for administrative purposes. Some Regimental Combat Teams were also categorized as brigades. Some Inner Sphere militaries would also use the brigade term to refer to major commands with a shared heritage and naming scheme.
Examples of BattleMech brigades include the Eridani Light Horse, Northwind Highlanders, Deneb Light Cavalry, or the Sword of Light. The Armor and Infantry units of the Federated Suns' Regimental Combat Teams are also referred to as brigades.
A Division is a grouping of three brigades, as well as reserves, support units, and an ASF Wing. They were commanded by a Major General or General. The Division was the heart of the SLDF, and was typically assigned to protect a group of star systems within one jump radius of each other, or a particularly important planet. SLDF 'Mech Divisions were modelled after the German Panzer Divisions of the 20th century. There are no division-sized formations known to exist in the Inner Sphere.
The ComGuards use the term Division to refer to their Level IV units, which consist of 216 combat units. In reality these units are approximately the size of two mixed regiments of 'Mechs, conventional armor, and infantry.
Used only by the SLDF, a Corps was a group of military forces that defended between 30 and 100 worlds. Unlike regiments, brigades, and divisions, there was no "standard" or "typical" corps. They typically consisted of one to three BattleMech divisions, two to seven infantry divisions, several independent regiments, and enough WarShips and transport JumpShips to move the entire unit. Each Star League Member State hosted between one and four Corps-sized units.
Later military planners would consider a corps a group of five to ten divisions, but didn't organize them by type (infantry, BattleMech, etc.).
As units of this size became impossible due to the damage of the Succession Wars, the term fell out of common military parlance until the Com Guards reactivated it to describe their Level V units. These units, like the SLDF Corps and Armies that preceded them, covered large parts of each of the Successor States, each of the then-twelve armies covering an "hour" on the "Inner Sphere Clock". Unlike the SLDF, a Com Guard Army is mostly an administrative term. The Battle of Tukayyid and Operation SCOUR were the only times ComStar deployed Army-sized formations in combat.
Typically an Army consisted of three to five Corps.
While the BattleMech organizational structure is common, there are two other unit types that engage in combat operations both in space and on the ground.
As mentioned earlier, aerospace units are half the size of BattleMech units (a lance has two fighters as opposed to four 'Mechs). DropShips and JumpShips are normally not grouped together, but are treated as independent support troops.
Typical Inner Sphere formation consisting of 2 - Aerospace Fighters, Conventional, VTOLs, WiGE type craft. In the Capellan Confederation a Flight is made up of 2 Squadrons, while the 2-3 fighter formation is known as an element. 
A formation used by CCAF Aerospace fighter groups. It is composed of 3 aerospace fighters that serves as the command unit and focuses on defense.
Typical Inner Sphere formation consisting of 6 units or airborne vehicles. Consisting of 3 flights. This does not include a Command Flight for the unit's commanding officer.
Typically Battalion size formation, consisting of 18 airborne vehicles. Not counting a Command Flight of 2 additional aerospace vehicles.
Consisting of 2 to 3 Wings of airborne vehicles, including Command Flight.
Infantry is divided into slightly different organizational units that can be integrated into traditional BattleMech units. The structure of an infantry unit is shown below:
- Fire team - consists of three to five individuals
- Squad - comprised of two fire teams and a squad leader (seven to twelve individuals)
- Platoon - comprised of two or more squads plus support personnel (twenty-five to fifty individuals). In the 3025 time period the standard platoon had one support weapons squad and three "line" squads.
- Company - comprised of two or more platoons (seventy to over two hundred individuals)
- Battalion - comprised of two to six companies (three hundred to one thousand individuals)
Combat in the thirty-first and thirty-second centuries has placed far less emphasis on infantry than previous conflicts so it is unusual to see infantry units larger than a company in size. It is common for squads and platoons to support BattleMech operations and to perform general patrol and scout duties.
Infantry units equipped with Battle Armor are organized differently from their conventional counterparts, due to their increased combat performance. Organized similarly to BattleMech units, Battle Armor units use the following structure.
- BattleTech, 2nd Edition, p. 26
- Field Manual: Capellan Confederation, p. 36, "Mixed Unit Organization And Command Doctrine"
- Strategic Operations, p.337
- Field Manual: 3085, pp. 19-20, "The Augmented Regiment"
- Total Warfare, pp. 34-35, "Military Organization"
- Field Manual: Draconis Combine, p. 17, "Unit Organization"
- Mercenary's Handbook, p. 68, "The Eridani Light Horse"
- House Davion (The Federated Suns), p. 81, "Prince Joseph The Second"
- House Davion (The Federated Suns), p. 126, "Aerospace Units/Armored Units/Infantry Units"
- Field Manual: Federated Suns, p. 22, "Infantry Units"
- Field Manual: Federated Suns, p. 18, "Force Structure"
- Field Manual: Federated Suns, p. 22, "Battle-Armor Units"
- Field Manual: Lyran Alliance, p. 21, "Types Of Units"
- Field Report: AFFS, p. 5, "The Light Combat Teams"
- The Star League, p. 133, "Unit Composition"
- The Star League, p. 138, "Regular Army 'Mech Division"
- Total Warfare, p. 34 - Organization - Lance/Battalions/Platoons - Flight description.
- Field Manual: Capellan Confederation, p. 33, "Standard CCAF Aerospace Organization"
- Total Warfare, p. 214, "Battle Armor Organization"