Stellar Fleets

The Imperium’s interstellar ships comprise merchant vessels, warships, civil craft, and several other specialised types. These are organised into specific fleets: merchant fleets, battlefleets, and civil fleets. Each of the Segmentae Majoris has its own merchant, civil and naval fleets. So for example, Battlefleet Solar is the warfleet of Segmentum Solar; Merchant Pacificus is the merchant fleet of Segmentum Pacificus; Civilis Tempestus is the civil fleet of Segmentum Tempestus, and so on.

Segmentae Registration

All interstellar spacecraft are registered as belonging to one or more of the Segmentae fleets. Registration allows a ship to be identified and permits the fleet authorities to record and administrate shipping within each of the Segmentae. A ship that is not registered in a Segmentae may only travel to that Segmentae with the special permission of the fleet authorities. This is purely an identification measure. An unidentified and unregistered ship may be assumed to be hostile, and attacked or destroyed.

The Merchant Fleets

The combined merchant fleets comprise almost 90 percent of all stellar spacecraft in the Imperium. Each fleet is based in one of the five Segmentae Majoris, and its records and associated administrative staff operate from the Segmentum Fortress for that Segmentae. For example, the Solar fleet is based on Mars, whilst the fleet of the northern zone — Segmentum Obscura — is based on Cypra Mundi. Although these fleet bases are huge ports equipped with docks, shipyards, and repair facilities, their main function is to administrate the fleets operating within their area. Only a small proportion of ships ever travel to the Segmentum Fortress where they are theoretically based.

Each merchant ship serves its fleet under an arrangement called a Merchant Charter. Not all charters are the same; some confer more power and responsibility to the ship’s captain than others.

There are different types of Merchant Charter. All types take the form of a feudal oath sworn to the fleet authorities on behalf of the Emperor. A captain may not register his vessel with the fleet authorities until this oath has been sworn and a record of it entered at the Segmentum Fortress for that zone and on the Segmentum Fortress on Mars.

A Fleet Charter is the least prestigious level of interstellar captaincy, and is also the least secure. A Fleet Captain may be deprived of his command and given a shore posting at anytime, and his ship reassigned to someone else. A Fleet Captain is appointed to his position in exactly the same way as a free captain, but plies fixed routes like the Hereditary Captain.

A more desirable form of merchant charter is the Free Charter. So-called Free Captains are appointed to command individual vessels by fleet officials. They are usually established fleet officials themselves, having worked their way up the ranks to a position of responsibility. Free Captains may trade as they wish within the fleet Segmentae, except that they are usually forbidden from trading along established routes. Instead, they roam the less densely populated and unexplored sectors, areas where regular services are either not needed or would be too costly to run.

Less common, but far more sought after, is the Hereditary Charter. A Hereditary Captain may nominate his successor, and that successor may swear the oath of allegiance and thereby becomes the new captain of the ship when its current captain dies or retires. As well as inheriting a ship, the captain inherits a route or routes, and is obliged to carry cargo and passengers only along this route. Some routes are more profitable than others and so are more highly regarded.

A Hereditary Free Charter is the most coveted and highly honoured form of captaincy. It is also the most ancient. A captain may be raised to a Hereditary Free Captain as a reward, but Hereditary Captains are no longer simply created as once they were. The captain is free in that he may trade freely within the confines of the Segmentae where his fleet is based. Most of these old captaincies are members of more than one Segmentae fleet, and some are registered in all five of the Segmentae Majoris. Although the Hereditary Free Captain is theoretically an imperial servant, his obligations are relatively few. The ship may trade where and how it pleases within the confines of its charter.

Civil Fleets

Although the vast majority of interstellar spacecraft are part of the merchant fleets, there are still many ships registered to individuals, families, or trading cartels. All privately owned interstellar craft operate along routes licensed to them by the fleet authorities responsible for shipping within that Segementum. These route licences must be bought, and must be renewed after a fixed time, usually a hundred years. This means few privately owned ships like to risk the effects of time dilation on long journeys. A licence may run out before the ship has completed its journey.

Civil fleets usually bid for route licences as they come up, the route going to the fleet prepared to pay the most for it. This system enables the Imperium to maintain routes, which, for whatever reason, it finds inconvenient to service from its own spacecraft. It is also a good way of raising revenue.As well as route voyages, the fleet administration also issues one-off licences for single trips. Many of the smaller fleets manage to survive entirely in a hand-to-mouth fashion reliant upon one-off licences.

Civil fleets vary in size from a single vessel to several dozen. One of the largest is that of the Navigator family Redondo, numbering forty-seven registered interstellar ships. Most ship owners have only a single vessel. Exactly who captains a privately owned ship is entirely up to the ship’s owners. In many cases the owner is also the captain. With the larger fleets, the owning body appoints a captain who is effectively an employee.

Imperial Navy Battlefleets

Each of the five Segmentae Majoris maintains its own Segmentum fleet, which further subdivided between sectors. Most space battles take place around installations or planets, which can be defended efficiently by sub-stellar craft and planet-based defences. Even so, it is impossible to provide total defence for every Imperial world. The battlefleets are highly mobile and extremely potent weapons, able to gather to meet large threats where necessary.

Although based in a Segmentae like merchant fleets, naval ships are universally registered — so a ship from one zone may be recognised in any other. This makes possible cooperation and coordination of naval forces, should the Imperium face such a threat that not even a Segmentum fleet can contain, and reinforcements must be called in from far and wide.

Naval captains are Imperial servants like their merchant brethren. However, all warship captains are appointed by the administrative officers of the Segmentum and have no rights of ownership regarding their vessels. The organisation of the fleets is far more rigid than that of the merchant fleet, with a hierarchy similar to that of the land-based armed forces of the Imperium.

Lord High Admiral

The highest ranking of the military officers is the Battlefleet Commander, or Lord High Admiral. He is in charge of the entire naval contingent of a Segmentum. There are, therefore, only five of these individuals. They rank equally, although command of the Battlefleet Solar is regarded as the more prestigious position. The Lord High Admiral formulates fleet-strategy throughout the entire zone, overseeing repair schedules, supervising construction programs, and ensuring the general space-worthiness of the fleet. His personal staff is divided into armament, maintenance, procurement, construction, and a thousand other working committees.

Sector Commander

Under the Battlefleet Commander are individual Admirals responsible for naval operations within each sector. The Admiral is based at the Segmentum Fortress, along with other sector-level administrative staff of the Administratum and other branches of the Adeptus Terra. He must answer not only to his naval superior, the Battlefleet Commander, but also to the Adeptus prefect in overall charge of the sector. The Sector Commander has direct command of a portion of the warfleet, and the duties of his ships are divided up into patrolling, permanently stationed and reserve fleets. The reserve fleet is usually stationed on the Segmentum Fortress. The remaining portions are placed under the command of Group Commanders.

Group Commanders

Group Commanders are Commodores and Rear Admirals in charge of a portion of a sector’s fleet. They are sometimes based around the Segmentum Fortress, or more often, on one of the permanently manned docking stations in one of the sub-sectors. Group Commanders are responsible for patrolling and keeping order within sub- and inter-sectors around their base. A typical command consists of a sub-sector base, non-combatant staff, and a couple of squadrons of ships. One squadron might be a light patrol squadron, whilst the other would only fly to meet specific threats.

Squadron Leaders

Squadron leaders are in charge of squadrons in space. They are also captains. A typical squadron might be three spacecraft of which the Squadron Leader’s ship is one.


Captains are in charge of individual ships. The term ‘captain’ is used to describe the officer in charge of a ship, but on the smallest of vessels the officer may in fact hold a rank such as commander or lieutenant-commander.

Temporary Battlefleet

Imperial space is so vast, with so many star systems and areas of wilderness space to be patrolled, that even the many thousands of spaceships in the warfleets must be spread thin, with individual ships and squadrons set out on their own assignments. The Imperium cannot maintain permanent fleets ready to respond to invasion or rebellion. Nor would it make sense to do so, for it would take so long for a fleet to get from its base to the warzone that the enemy would surely have moved on by the time it arrived.

Instead, temporary battlefleets are gathered together whenever they are needed. Warships within a relatively small area are summoned to join the battlefleet. It is rare for ships more than fifty light years from the battle zone to be included in the fleet, and more commonly only those within a dozen or so light years are summoned. Even with ships this close to the battle, it will take at least days and more often weeks for them to arrive.

Only during the very largest of wars, lasting for many decades, does the Imperium bring battlefleets together and dispatch them en masse to a warzone. Many such wars are currently underway, such as the conflict raging in the galaxy’s south-eastern spiral arm. Here the Tyranid Hive Fleets are inexorably advancing, conquering and consuming every planet in their path. A massive campaign involving millions of men, thousands of ships, and whole chapters of Space Marines is being fought against the Tyranid invasion. Fleets are being mustered far and wide to undertake the long journey to the warzone. The journey will take decades, in some cases, and many of the crew will never see the battles they are heading towards. But the Imperium knows all too well that in mere decades the Tyranids might consume the entire Eastern Fringe.

Enemies of the Imperium

The battlefleets of the Imperium must combat many enemies — Ork raiders, Eldar pirates, the Tyranid Hive Fleets, and other alien invaders. It must also fight forces from within the Imperium itself. Most of these battles are small-scale and involve only sub-stellar craft in skirmishes with smugglers, brigands, and rebels. But occasionally, larger conflicts occur when whole systems or groups of systems must be brought into line. Sometimes these systems have their own fleets, and the Imperium must send its largest battleships and cruisers to crush the enemy. In these circumstances an Imperial Navy battlefleet will be facing an enemy containing ships exactly like its own.

These rebellions most often happen when an area of the Imperium is cut off by a warp storm. Warp storms are common occurrences and systems frequently lose contact for years at a time. When the storm passes, contact is re-established and little will have changed. Sometimes storms last for decades, even centuries, and systems cut off for this long can stray far from Imperial authority and orthodoxy. Once the warp storm has died down and travel to the system is feasible again, the Imperium may be rebuffed by an independent federation or find itself in the midst of a local war. A battlefleet will be assembled to return the system to Imperial control, and Imperial Navy spaceships will find themselves facing ships that perhaps once served alongside them in other wars.

It is also not unknown for squadron or fleet commanders to rebel and turn against the Imperium, using the awesome power they command to carve out their own petty empires on the fringes of the Imperium’s space.

Worse still are such civil wars such as the Horus Heresy, when Warmaster Horus turned to the worship of the Ruinous Powers and led fully half of the Imperium’s forces against the Emperor. Only the death of Horus himself and the banishment of his followers to the hellish regions of space called the Eye of Terror brought an end to the uprising. Even ten thousand years later, a constant vigil is kept around the Eye of Terror where the Chaos fleets remain, often launching small raids and occasionally major incursions into the Imperium.

Stellar Fleets

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