The Astra Militarum and Imperial Navy

The Imperium at War

The Imperium survives through military force on a scale few civilizations can equal.

Every day, armies fight across fortress worlds, hive cities, deserts, jungles, void stations, ruined colonies, and worlds whose names may never reach Terra.

The Astra Militarum and Imperial Navy form the foundation of most Imperial campaigns.

The Militarum fights upon planets and stations.

The Navy carries those armies between systems, protects transport routes, controls orbit, and battles enemy fleets.

Neither can wage a major interstellar war effectively without the other.

The Astra Militarum

The Astra Militarum, also called the Imperial Guard, is the Imperium’s largest organized ground force.

Its strength comes from the soldiers, vehicles, artillery, officers, and support personnel raised from thousands of different worlds.

A Guardsman may come from:

• A fortress world

• A hive city

• A death world

• An agri-world

• A noble household

• A mining colony

• A feudal society

• A penal population

• A voidborn community

• A newly conquered planet

These soldiers may possess very different cultures, equipment, tactics, and expectations.

They are united by Imperial command, military discipline, assigned objectives, and the knowledge that failure may condemn entire worlds.

Regiments and Home Worlds

The regiment is one of the Astra Militarum’s central military organizations.

Regiments are normally raised from a particular world or population and often preserve that world’s traditions.

One regiment may specialize in siege warfare. Another may excel at armored assaults, reconnaissance, artillery, jungle fighting, mountain warfare, urban combat, or rapid deployment.

Home-world culture influences:

• Uniforms

• Weapons

• Training

• Religious customs

• Command style

• Attitudes toward outsiders

• Battlefield doctrine

• Treatment of psykers and abhumans

• Expectations of honor and sacrifice

Regiments are frequently deployed far from home.

Many soldiers never return.

This separation reduces the risk that military commanders will become too powerful within their own societies, but it also leaves regiments dependent on unfamiliar supply systems and distant authorities.

Infantry, Armor, and Artillery

The Astra Militarum relies upon combined arms.

Its forces may include:

• Infantry squads

• Heavy-weapon teams

• Armored vehicles

• Artillery batteries

• Reconnaissance units

• Combat engineers

• Sanctioned psykers

• Commissars

• Priests

• Medicae personnel

• Ogryn auxiliaries

• Ratling scouts

• Tempestus Scions

• Planetary support forces

The Guard often wins through discipline, preparation, numbers, firepower, fortification, and willingness to endure losses.

Its soldiers are ordinary humans facing enemies far stronger than themselves.

Their courage lies not in being fearless, but in holding their position despite fear.

Command and Discipline

Astra Militarum command passes through officers, staff personnel, strategic planners, and military authorities responsible for campaigns spanning worlds.

Orders may be clear and practical.

They may also be based on outdated maps, incomplete intelligence, political demands, or assumptions made far from the battlefield.

Officers must balance obedience with local reality.

Commissars enforce morale, discipline, and loyalty. They may inspire soldiers, investigate cowardice, execute deserters, confront corrupt officers, or prevent panic from spreading through an army.

Not every Commissar is identical.

Some are respected leaders. Others rely on fear. A skilled Commissar understands that soldiers fight better when they believe their sacrifice has purpose.

Planetary Defence Forces

Most Imperial worlds maintain their own Planetary Defence Forces, commonly called PDF.

The PDF protects local territory, supports law enforcement, guards strategic sites, and serves as the first defense against invasion or rebellion.

Its quality varies enormously.

A fortress-world PDF may be disciplined and heavily armed. A corrupt hive-world force may exist mainly to protect noble districts. A frontier militia may know the local terrain better than any outside regiment.

When a crisis grows beyond local control, the Astra Militarum may be called to intervene.

PDF units may fight beside the Guard, collapse under pressure, become infiltrated, or resent outside commanders taking authority.

The Imperial Navy

The Imperial Navy controls most major Imperial warships and interstellar military operations.

Its responsibilities include:

• Fleet combat

• Planetary blockade

• Orbital defense

• Troop transport

• Convoy protection

• Patrols

• Anti-piracy operations

• Bombardment

• System security

• Escorting strategic cargo

• Supporting invasions

Imperial warships are enormous, ancient, and heavily crewed.

A single vessel may contain officers, ratings, armsmen, Tech-Priests, Navigators, astropaths, servitors, gunners, pilots, laborers, prisoners, clergy, and families who have lived aboard the ship for generations.

Void War

Void battles take place across immense distances.

Ships maneuver for firing positions, launch attack craft, deploy torpedoes, exchange broadside fire, conduct boarding actions, and attempt to cripple enemy engines, weapons, shields, or command systems.

Victory may depend upon:

• Position

• Intelligence

• Fleet coordination

• Navigation

• Morale

• Damage control

• Ammunition

• Fighter support

• Boarding actions

• Control of local space

A ship can survive catastrophic damage while losing thousands of crew.

Captains must decide whether to preserve the vessel, complete the mission, rescue allies, or sacrifice themselves to destroy a greater threat.

Transport and Deployment

Moving an army is a major operation.

Troops, tanks, artillery, ammunition, fuel, food, spare parts, medical supplies, and replacement personnel must all be transported through the Warp.

Once a fleet reaches a system, forces may deploy through:

• Landing craft

• Shuttles

• Drop ships

• Orbital stations

• Space elevators

• Fortified ports

• Mass landers

• Teleportation in rare cases

An invasion can fail before the first major battle if transports are lost, landing zones are compromised, supplies are misdirected, or the Navy cannot hold orbit.

This makes ports, void docks, fuel depots, translation points, and transport vessels strategically important locations.

Divided Authority

The Astra Militarum and Imperial Navy are separate institutions.

A ground commander may control armies without possessing authority over the fleet carrying them. A naval admiral may control orbit while refusing a request considered too dangerous or wasteful.

Disputes may concern:

• Landing schedules

• Orbital bombardment

• Evacuation

• Supply priority

• Fleet protection

• Civilian casualties

• Strategic withdrawal

• Which target matters most

• Whether a planet can still be defended

Political officers, Inquisitors, governors, Mechanicus representatives, and Space Marine commanders may further complicate command.

A campaign can contain several authorities, each with legitimate but conflicting objectives.

Logistics and Supply

Armies depend on supply.

Lasgun charge packs, artillery shells, fuel, food, water, replacement parts, medicae resources, uniforms, and reinforcements must reach the correct units.

Supply failures may result from:

• Warp delays

• Enemy raids

• Corruption

• Bad records

• Damaged roads

• Lost transports

• Rival commands

• Sabotage

• Desertion

• Misidentified cargo

• Political favoritism

A regiment may possess strong morale and skilled leadership but still collapse when ammunition runs out.

Logistics should create adventures rather than only background frustration.

Characters may escort convoys, recover fuel, reopen a route, identify a saboteur, defend a depot, or decide which unit receives limited supplies.

The Cost of War

Imperial commanders often think in terms of territory, regiments, ships, and strategic objectives.

The people inside those numbers still matter.

A victory may leave survivors without homes. A regiment may be destroyed holding a position nobody outside the sector remembers. A naval bombardment may save an army while killing the population it intended to defend.

Franz should show both military necessity and human consequence.

Commanders may face choices with no clean solution.

Players should have opportunities to reduce losses, challenge poor orders, preserve lives, or accept terrible costs for a larger objective.

Soldiers as Player Characters

A player character may serve as:

• Guardsman

• Officer

• Scout

• Commissar

• Combat engineer

• Sanctioned psyker

• Naval armsman

• Pilot

• Voidship specialist

• Deserter

• Penal soldier

• Veteran

• Mercenary attached to Imperial forces

Characters serving in military organizations should still possess room for personal decisions.

Orders create objectives, but they should not remove all choice.

The party may determine how to complete the mission, which risks to accept, whom to trust, and whether an order remains lawful, practical, or morally defensible.

Mass Warfare in Play

Large battles should remain focused on character-scale objectives.

Rather than resolving an entire war through ordinary attack rolls, Franz should place the party at critical points.

Possible objectives include:

• Holding a gate

• Destroying artillery

• Capturing an officer

• Repairing a defense system

• Rescuing a surrounded unit

• Guiding an air strike

• Securing a landing zone

• Boarding an enemy vessel

• Protecting a command staff

• Exposing false intelligence

• Recovering battle plans

• Preventing retreat from becoming a rout

The outcome of these missions can affect the larger battle.

The characters are not expected to defeat an army by themselves.

They matter because they act where a small group can change what happens next.