Greetings!

In our current RT group, I am playing an explorer from a Fortress world. And the thing I am wondering, is how do they really work?
I mean, why not just bypass them, in the warp if need be? And, even if you cant/dont, why land troops there, instead of just continuing on? Do the worlds have such powerfull ground-to-orbit weapons so that any fleet that wants to get through, are going to lose so many ships that they need to make landfall and take the world?

In general, any fluff or ideas you have regarding this would be much appreciated, since I am currently trying to write up a background.

Cheers!

My understanding of Stratega Imperialis (and the greater WH40K universe)

Large stellar bodies such as stars or planets have a certain radius in which you cannot Warp into/out of, giving defenders time to respond.

Warp travel is faster through some areas than others, and can vary based on Navigator skill. Therefore, some strategically located worlds are great sites for powerful reaction forces to be stationed. If any forces of the Enemy were to penetrate Imperial Space without first subduing these Fortresses they would be vulnerable to quick-reaction forces from said Fortresses.

Secondly, worlds like Cadia are situated near the only stable warp path out of the Eye of Terror (according to fluff, that is) and therefore are crucial choke-points.

Finally, many worlds near the Eye of Terror have Necron built Pylons which were part of there secret project to close off the galaxy from the Warp, forever. Although they never finished their project, these pylons seem to limit the expansion of the Eye of Terror and also stabilize the space around them. The specifics of these effects weren't detailed in the works I've read.

Think of them as colossal barracks. They have sufficient men-at-arms and fleet vessels stationed there to take on most anything that comes within range of them. You'd also have them protecting other critical worlds in a system.

Firstly: Rule of Cool. Entire worlds as fortresses are cool, ergo: they exist.

beyond that they are like castles. Sure you can go and sack the countryside but if you don't deal with the castle, then the forces stationed there can sally forth and get you when you're vulnerable. Also, if forces in the region need to be reinforced then it provides a safe place for them to marshal.

I'm not 100% sure how 40k works in terms of warp travel, weather or not you can (generally) jump to any system (like star trek), or weather or not you need to 'hop' from system to system (like star wars). the you need to hop, then obviously you place a fortress world at a choke point. If you can jump anywhere then a fortress world acts like a castle, plenty of forces stationed there ready to assault anything within reach.

Agmar_Strick said:

This much is frequently true - due to being highly militarised in their own right, fortress worlds commonly produce large quantities of Imperial Guard regiments to support other warzones across the Imperium.

Agmar_Strick said:

Fundamentally, both are true - a skilled Navigator can direct a voidship anywhere through the Warp, but the overwhelming majority of warp travel is performed along established, stable routes - the points where these routes converge are frequently fortified, as they're often the target of enemy attacks.

While most has already been said, I want to add a comparison.

Think of the ocean on earth as the void. Sure you can have ships go everywhere. But it's still good to have a save place to anchor, make repairs, resupply.

Just like pearl harbor was important during WW2, even if the ships, including the aircraft carriers, could have just gome around it was still being fought over.

It was no fortress (in the sense of a fortress world in 40k) so the first attack was rather devastating.

Think of a fortress world as something that has no farmland but is plastered with barracks, bunkers and huge anti ship weapons for both, preventing enemy landing and destroying ships in low orbit that could bombarde the planet.

Around the planet there are no nice space stations but orbital bunkers, sentry guns and space-mine fields.

One major use of some fortress worlds is as glorified supply depots. In fact Forge World produced a trilogy of books revolving around a campaign to recover just one such world that had fallen into the hand of an apostate cardinal.

Basically the imperium has places that actually end up producing a surplus of goods that will be needed at some point in the future, or that require a centralized hub for shipping to areas that require certain things like food, and nuclear weapons. Things like older equipment that's being phased out but might be useful, WMDs of various designs, mundane tools of warfare like guns, and in some cases things like astartes geneseed or holy relics.

So the adeptus ministorum finds a planet that's not extremely useful and turns it into a glorified equipment storage shed, assigns some forces to it, and then sets about the task of making it defendable. Once things get going they tend to progress unless an outside factor (Such as tyrannids eating everyone) stops progress, leading to an ever growing series of underground storage and aboveground fortifications.

There are also worlds given over to the sole task of keeping people away from them which are also likely to become fortress worlds. Places with 'things best left dead' or the aforementioned gene seed repositories are good examples of planets given over entirely to housing troops and strong defenses. Generally these garrisons aren't the kind you get rotated out of, with the defenders staying until they die, and new ones brought in without being told what happened to the former occupants.

These are in addition to worlds that are intended to be such obvious thorns in an attacker's backside that they need to be taken out before the real objectives can be assaulted.

- Glorified stores house

- Sentralised hub

- Training & production ground for IGuards

- Vault for forbidden items/ knowledge

- Last Stand Worlds (a race being assaulted on a wide scale may create those "arch" or "last stand worlds". Huge impenetrable fortress to house thier falling society...

- etc

Thanks, that was just what I needed to get going with my writing
While I am finishing up my background, I have made a simple Planetary Date file, if you guys have any suggestions on improvments, or just want to say "Thats so wrong you idiot!", please go ahead

Planetary Data

Population: Esimate indicates 160 million people, from a recorded previous height of 220 million. Heavy losses where suffered during a planetary invasion in 812.M41.

Tithe Grade : Exactus Majoris, the millitant focus of the world makes it ideal for a high tithe grade to the Imperial Guard.
Geography/Demography: Temperate climate, with breathable but unpleasant air. The northern part of the world is constantly turned away from the star, leaving it in perpetual darkness and twilight. The southern part are devoid of life, and is a barren wasteland. The northern part is mainly mountains and craters, with a small amount of vegitation (Just barely enough to keep the air breathable. The Adeptus Mechanicus has a few Adept-biologist's trying to increase the natural vegitation.). Lychantos: capital/starport/planetary fortress. Maintaining several ground-to-orbit weapons, as well as extensive anti-air and artillery defenses, the fortress is built into, and around, the largest mountain on Marsara. The whole population makes this town (I use the word in it's most literal sense) their home, the majority living in the undergound levels, the topside being completely under military command to maximise the defensive capabilities(And to limit morale loss when their would-be homes get razed as defensive countermeasures).

Governmental Type: Military dictatorship.

Planetary Governor: Governor-Militant Linette Drussili(Perhaps connected by blood to Saint Drussus, investigation pending). Officially, she only holds the rank of Mayor, to simplify the use of the planets Regiments for Imperial Guard duty, avoiding General to General conflict of interest. There is no doubt however, that the general populace see her as their General.

Adept Presence: Adeptus Administratum, medium presence. Adeptus Ministorum, medium presence. Adeptus Arbits, minor presence(The militant focus, high morale and patriotism, aswell as the extremly large quantity of PDF troopers makes crime virtually non-existant. Only a token force of Arbites make Marsara their home, most being as capable soldiers as the PDF, if not more.).

Military: Currently, there exists 375 active Marsaran Imperial Guard regiments. Becuse they spend so much time in each others company, the regiments see no reason to follow the tradition of being single-sex regiments. Records indicate that around 37-42% of the soldiers are women, spread fairly evenly amongst the regiments. In addition, aproximetly 85% of the population is either a part of, or has previously been a part of, the Marsaran Defence Army(PDF). The rest of the population has also recived basic weapon training. The proverb that on Marsara there exists twice as many lasguns as people is, however, completely untrue. The Administratum estimates that there only are 1.4 lasungs per person. A defensive fleet lies in permanent orbit around the planet, wich in conjunction with the planets powerfull ground-to-orbit weapons makes it a powerfull fleet.

Trade/Economy/Addendum: Light-to-non-existant off-world trade, Marsara being completely devoid of natural resources, with the exception of a minor vein of minerals that can be turned into promethium, but this is sololy used to power the various armour on the planet. All food, weapons, ammunition etc. are brought in off-world. Thanks to extensive underground storage facilities, Marsara, when fully stocked, can endure a 5 year long siege.

The population is only 160 million - a smallish Hive World has about 20 billion.

I'd suggest upping it to about 8 billion - remember that not everyone on a Fortress World is a soldier, they also have people working in the arms factoriums and the like.

MILLANDSON said:

The planet has marginal habitablility, so a small pop is not out of bounds. It isnt a hive world.

That was kinda what I was going for, and in comparison, Cadia has a population of 250 million, and I wanted this to have the "Small outpost on the edge of the known universe"-feel. Or, as close to "small" as it gets in 40k

@Nightsorrow;

I actually signed in just to complement you on your planet discription. It sounds pretty cool, especially the "small" scale, since my problem usually is to use the 'big numbers" way to often. Its nice to see that a lot of ideas are also possible with smaller numbers.

Well, big / small, as you stated, big and small are also relative in WH40K