I often think that it is hard to grasp the scale of the Imperium. I think a lot of 40k material consistently underestimates or misaligns scale. I like certainty and order in a setting; however, given the nature of 40k, a multi-author universe with hundreds of different interpretations, I'm unlikely to ever get it.

Nevertheless, I'm going to crunch some numbers. I'm going to attempt to set out my own interpretation of the scale of various facets of the Imperium, and you can tell me if these numbers ring true or not. I'm going here more on "gut feel" than canon sources, but if you are able to retort with evidence based on the canon that shows I'm wrong, by l means do so!

How many planets are there in the Imperium?

Multiple sources in the canon describe the Imperium as "an empire of a million worlds." The 1,000,000 number is one I never used to like, as I kind of want the Imperium to be bigger. After all, there are potentially several tens of billions of inhabitable worlds in the galaxy. However, the number is pretty ingrained.

Of course, it's obvious that no one in the Imperium knows exactly how many worlds it contains. it's like trying to say "how many people are currently riding on the London underground"? or "How many pigeons are currently flying over New York?" In the time it takes to ask the question, the number has changed, and it changes again in the time it takes to answer, and every second thereafter. New worlds are always being discovered, other worlds are being lost.

If we take it as read that the Imperium has "about" a million worlds, though, this does give us a starting point of sorts.

How many sectors are there in the Imperium?

My gut feel, based upon what we've seen of Imperial Sectors that are fairly well detailed in the Canon like the Scarus and Calixis sectors is that a "typical" Sector has about 200-250 inhabited Imperial worlds within it.

Of course, within the geographical boundary of the Calixis sector there will also be tens, possibly hundreds of thousands, of uninhabited and largely unexplored worlds.

If we assume (I know, I know, it's a big assumption, and I freely admit I could be wrong) that there are 200-250 worlds in each Sector, then just on numbers alone we're looking at somewhere between 4,000 to 5,000 Sectors.

These numbers feel about right to me. Figures in this region mean that there are 4 or 5 Sectors for every Space Marine Chapter, which gels well with their being a rarely seen force to the vast majority of citizens within the Imperium. Assuming most Chapters are based within Imperial space (I know,assumptions assumptions) this means that about 1 in 4 or 1 in 5 Sectors has a space marine chapter based somewhere within its boundaries.

How large is a Sector Battlefleet?

Again, this is a gut feel, there's no canon source for this, but I have always felt that the Imperial Navy has a 1:1 planet:ship ratio for its battlefleets. So a sector with 213 planets would be allocated 213 ships by the Imperial Navy.

I know I'l get criticised for plucking these numbers from thin air, but all I can say in my defence is that a 1:1 inhabited imperial world:imperial navy ship ratio feels right. It has a brutally simple logic to it, the sort o logic one can imagine an administratum scribe backing.

A Sector battlefleet might consist of a handful of battleships, 20-50 cruisers, and the remainder of the fleet would consist of escorts, frigates and light cruisers.

This sounds like a powerful force, but those 213 ships have to guard not only individual worlds, but the space lanes between them, and conduct patrol sweeps across the vast areas of wilderness space between the Sector's inhabited worlds.

How large is a Sector Merchant Fleet?

The Rogue Trader RPG describes the merchant fleets as amounting to around 90% of space traffic. Assuming that the space marine fleets, arbites fleets, black ships and the imperial navy between them make up the remaining 10%, then there's going to be a ratio of at least 9:1 for navy: civilian vessels. Meaning that in our theoretical 213 planet sector, there will be at least 1,917 civilian ships plying the space lanes, probably in practice more like 2,000.

Again, there is no canon source for this; but these numbers feel right. This number of ships would make the colossal crusades of the Imperial Guard feasible, and they would allow trade between worlds within and outside the Sector.

Anyway, what are your thoughts on these numbers so far?

Maths was never my strong point.

But from my perspective I'd say you're certainly close to the mark with your number crunching. My point of view, while reading your hard work, is that it does indeed feel right.

Good job.

Pretty sure that most fluff will talk about the Imperium measuring millions of worlds, losing planets due to rounding errors etcetera. I agree that this number still seems sort of low, but I think you could take that as a subtle indication of the nature of the galaxy in the future. Humanity has a plan to consign planets to Exterminatus because of the actions of one hive city. Entire worlds are given over to pollution and inhospitability so that the AdMech can perform their weird little rituals. We're being invaded by hive mind omnivores, and accidentally based the foundation of our technology on a Star God that is waking up its immortal, robotic killers.

Bearing in mind that the Eldar empire is always described as having been bigger than the Imperium of Man, I think a combination of the Fall of the Eldar and the outright slaughter caused by the Horus Heresy resulted in the Galaxy actually losing a large portion of its habitable worlds by the 41st Millennium.

Wait, Imperial tech is based on Necrontyr stuff?

Sweet.

I always thought "a million worlds" was not an actual number but more of a superlative way of saying a **** lotta worlds we can't keep track of.

Then again, a million worlds sounds about right. Humanity is spread thin after all. Warp storms hem in routes, leaving entire areas dark and unreachable in the Koronus Expanse which should contain a few billion stars alone. Factor in the the unending war, pollution, various xenos empires (and their eventual demise), and it's not hard to imagine a million worlds is all the Imperium can muster. More or less.

Wait, Imperial tech is based on Necrontyr stuff?

No, but we have a C'Tan "dormant" at the heart of Mars, subtly influencing the Adeptus Mechanicus to believe in him, and make themselves more like him.

Wait, Imperial tech is based on Necrontyr stuff?

No, but we have a C'Tan "dormant" at the heart of Mars, subtly influencing the Adeptus Mechanicus to believe in him, and make themselves more like him.

Oh, the Void Dragon. I thought for a moment you meant something else.

on the number of worlds. i'd suppose that was to mean inhabited worlds. sooo i can't remember the name of the theory but it is used for intelligent species, but it applies here as well. we don't know but lets say 1 in 10 stars have planets. 1 in 10 of those have a planet in the "goldylocks belt" 1 in 10 of those have every thing it needs to support life. 1 in 10 of those actually support life. and 1 in 10 of those have an intelligent species. so only 1 in 10,000 stars have systems that can support life. and 1 in 100000 have an intelligent species. the galaxy has between 100 to 400 billion stars. let call it 250 billion. so 25 million stars can support life and 2.5 million have intelligent life.

just something to think about.

I agree that the numbers are (literally) astronomical, Austin. This is why I think that a 1,000,000 world Imperium seems a little small to me. But this 1 million number does seem to crop up again and again.

I like Erathia's point about the apparent relative dearth of inhabitable worlds in the Imperium possibly being due to the Fall of the Eldar and the Horus Heresy. That has to be true. Plus many of the Great Crusade era Legions (Death Guard especially) seem to have been quite trigger happy when it came to using exterminatus class weaponry.

even with the loss of a lot of planets there could easily be billions of planets by volume and 1,000,000 always sounded small to me. Also i think one 200 some ships in a sector would be far to low to patrol it with any success I would say the IN would need at least double that to be effective.

I think it would be impossible for the Imperium to patrol a Sector even half way effectively, let alone perfectly with double, triple or even ten times my nominal "200-250" figures. If there are tens/hundreds of thousands of dead/uninhabited/unexplored planetary systems in every Sector, then you'd need tens/hundreds of thousands of ships per sector to patrol it. Plus bear in mind you'd need to patrol the spaces between planets, too: space lanes, warp/realspace translation points on the outer edge of star systems etc etc. I don't think the Imperium would EVER have the resources to patrol space as effectively as they'd like.

I think the Imperium's Naval patrols in every sector would concentrate on defending/patrolling between key high priority targets/regions, in the following order of importance:

1. The Sector capital world (would always have a few Navy ships in orbit)

2. Major Imperial space docks/shipyards/naval bases ( ditto, but fewer)

3. Subsector capital worlds (would typically have at least one Navy ship present)

4. Major Forge worlds/major hive worlds (a ship would never be more than a few weeks away, might have a ship there half the year)

5. Major trade routes (so a ship might spend decades patrolling a major trade route: in the Calixis Sector this might be the trade route between, say, Iocanthus and Scintilla. Major trade routes which the Sector economy depends upon may have permanent ships/squadrons assigned)

6. Known trouble spots; areas of pirate/xenos activity and the like (might get a patrol through every couple of years)

7. Hive worlds (might get a Navy visit one every five years or so

8. "Imperial" worlds in good standing, so hive worlds, important agri worlds, frontier worlds with potential for strategic expansion , Universe-scale trading vessels etc (might get a visit from a Navy ship once a decade)

9. Lower priority Imperial worlds, frontier worlds and the like (might get a visit every 25 years or so)

10. Unexplored/uninhabited systems (might get a patrol visit every century or so)

So yeah, one ship per planet leaves the Imperial Navy stretched thin... But in a way that still allows interesting stories to be told!:-)

true enough but I still feel the number is rather low, Battlefleet Koronus is at least several dozen ships strong and its just a detachment, plus the margin crusade and i would have to assume there are more than the 200-250 in service to make al of the viable.

I think it would be impossible for the Imperium to patrol a Sector even half way effectively...

4. Major Forge worlds/major hive worlds (a ship would never be more than a few weeks away, might have a ship there half the year)

...

7. Hive worlds (might get a Navy visit one every five years or so

8. "Imperial" worlds in good standing, so hive worlds, important agri worlds, frontier worlds with potential for strategic expansion , Universe-scale trading vessels etc (might get a visit from a Navy ship once a decade)

...

So yeah, one ship per planet leaves the Imperial Navy stretched thin... But in a way that still allows interesting stories to be told!:-)

I agree with these statements. I also think it's important to remember that the Imperial Navy isn't the Imperium's only line of defense, merely the most mobile and dangerous of its void-borne forces. The Imperial Navy goes where fixed defenses simply aren't enough.

A good example are the locations I left above: Forge Worlds have their own defenses, between Mechanicus war vessels, system ships, and orbital defenses, there's very little need for an Imperial Navy ship to ever be there unless there's a major incursion happening nearby. Hive Worlds and Imperial Worlds too would likely have system ships and orbital defenses that would be enough to keep away the average pirate or xenos raid, or at least be strong enough to hold out until an Imperial Navy patrol can get there (see: the Damaris Campaign).

The thing I would be interested in seeing you calculate would be the total mass that the merchant fleet could trade between worlds regularly. If we know how many ships they have, and we have a decent idea of how big each ship is (the Vagabond for example), I'd be curious about how much stuff actually gets shipped between planets each year based on those numbers.

I'm pretty sure I've seen a reference to Battlefleet Gothic (that is, the Imperial Navy ships present to fight in the Gothic War, mostly from the Sector Fleet of the Gothic Sector, with some shortstopped on their way from elsewhere, some sent as back-up from other sectors, some pulled from a Reserve Fleet, and not counting any borrowed from other organisations, like the Mechanicum, the Inquisition, the League of Blackships, planetary governors' private fleets/SDF, Rogue Trader flotillas and the Astartes) at ~60 capital ships (that is, light cruiser or above), with an indeterminate (but much higher) number of escorts (frigates and destroyers), armed merchantmen, et cetera. Barely any grand cruisers*, iirc, and at most 5-6 battleships (offhand, I only recall the HDMS Cardinal Boras and the HDMS Divine Right for certain). I will search more thoroughly to find a confirmation or contradiction.

I feel, however, that I should point out that a Battle Fleet is a temporary organisation formed to fight a specific campaign/crusade. It doesn't really have any sort of fixed size, or even a pro-rated one based on the volume of Imperial-controlled space/number of planets comprising the theatre: it's whatever ships are present in theatre, and any that may be required if it escalates. It does normally comprise the sector fleet (or a part thereof) of and in which the conflict breaks out, and draws its name from that.

Sorry. My inner pedant insisted.

*Mostly because the Gothic Fleet didn't have any in service, and even the Gothic Reserve was noted to have at most a couple of Avenger/Exorcist class in mothballs that could be reactivated. The Cadian and Armageddon Fleets and Reserves, however, were noted as retaining more to play with. I guess it's a case of what was fashionable where, and what survived when fashions changed.

I think it would be impossible for the Imperium to patrol a Sector even half way effectively, let alone perfectly with double, triple or even ten times my nominal "200-250" figures. If there are tens/hundreds of thousands of dead/uninhabited/unexplored planetary systems in every Sector, then you'd need tens/hundreds of thousands of ships per sector to patrol it. Plus bear in mind you'd need to patrol the spaces between planets, too: space lanes, warp/realspace translation points on the outer edge of star systems etc etc. I don't think the Imperium would EVER have the resources to patrol space as effectively as they'd like.

<snip>

So yeah, one ship per planet leaves the Imperial Navy stretched thin... But in a way that still allows interesting stories to be told!:-)

Absolutely agreed, with just one minor detail:

Patroling systems is technically not the responsibility of the IN.

It is the responsibility of the SDF - System Defence Force - of the planetary governor. rather similar to (and often considered part of) the PDF of each planet. Their job is not to stop a dedicated attack force, but to slow them down and call for help. Exactly like the PDF.

Their main ships are system defence ships, as seen in HA. They also often hold a station above the planet, like the Bulwark of Damaris. In BFG, both of these were available only when acting as a defender in certain scenarios.

Some good thinking going on here. I'd like to put in my two cents.

There's a link with neat calculations of numbers of psykers and black ships:

http://www.warseer.com/forums/showthread.php?335682-Black-Ship-Logistics-Taking-a-stab-in-the-dark

Based on it I think there should be a lot of more planets in Imperium.

On p. 318 Only War there's a (almost literal) mention of more than a milion worlds and what's more interesting on p. 322 ibidem we've got info that there's about a milion of governors and some of them rule more then one world, while also there're worlds without governors at all.

No mention about one world being ruled by more then one governor

To sum up a milion worlds Imperium is imho just a rhetorical figure just like a thousend year reich.

To the number of ships. With Stars of Inequity we've got an option to have a IN frigate per colony in quite remote place Koronus Expanse is. Based on it I'd say more then one IN ships per established imperial planet.

Admittedly I don't have a clue how to get more balanced numbers and - of course - this is everyones Imperium to play with.

true enough but I still feel the number is rather low, Battlefleet Koronus is at least several dozen ships strong and its just a detachment, plus the margin crusade and i would have to assume there are more than the 200-250 in service to make al of the viable.

I don't have Battlefleet Koronus to hand, so I don't recall precisely the size of the units assigned to the Koronus Expanse...but I think it is worth noting that the Calixis Sector is probably an unsually quiet sector as far as fleet scale engagements are concerned. I seem to recall there hadn't been any major fleet actions for at least a couple of centuries.

My point is that the Battlefleet Calixis Admirals may be taking the view that the Koronus Expanse deserves aggressive patrolling far more than the relatively peaceful Calixis Sector. (Spinward Front aside). As a result, what appear to be disproportionate Battlefleet Calixis resources are being diverted into the Expanse After all, the Koronus Expanse possesses a nascent Ork Waaaagh! and the remnants of a technologically advanced warp tainted race...plus a warp gate into a Sector-scale conflict on the other side of the galaxy.

I'm not saying you're wrong in regarding my 200-250 strong fleet figures as low...after all, I freely admit that there are no concrete canon sources on Sector Fleet/Battlefleet size...but Battlefleet Koronus being large doesn't affect my thinking on the subject, really.

Absolutely agreed, with just one minor detail:

Patroling systems is technically not the responsibility of the IN.

It is the responsibility of the SDF - System Defence Force - of the planetary governor. rather similar to (and often considered part of) the PDF of each planet. Their job is not to stop a dedicated attack force, but to slow them down and call for help. Exactly like the PDF.

Their main ships are system defence ships, as seen in HA. They also often hold a station above the planet, like the Bulwark of Damaris. In BFG, both of these were available only when acting as a defender in certain scenarios.

True - but not every world is going to have a system defence force. Primitive feral or death worlds may well not have the resources to create such a local fleet, or even orbital defence platforms. Such fleets are less common than PDFs.

And even if there are local SD fleets, why would this stop the Imperial Navy visiting if they wanted to reprovision or just to show the flag? Just because New York has US Coastguard ships on standby in the vicinity, that doesn't seem to prevent US Navy vessels from dropping into visit the city from time to time.

System defence ships can be powerful, as can orbital platforms, but generally they lack the power to defend themselves against warp-capable deep space craft. If I was a Lord Admiral, I'd ensure that my ships "dropped in" to Imperial systems unpredictably from time to time to keep the local governors in line and to keep pirates and raiders on their toes.

I'm pretty sure I've seen a reference to Battlefleet Gothic (that is, the Imperial Navy ships present to fight in the Gothic War, mostly from the Sector Fleet of the Gothic Sector, with some shortstopped on their way from elsewhere, some sent as back-up from other sectors, some pulled from a Reserve Fleet, and not counting any borrowed from other organisations, like the Mechanicum, the Inquisition, the League of Blackships, planetary governors' private fleets/SDF, Rogue Trader flotillas and the Astartes) at ~60 capital ships (that is, light cruiser or above), with an indeterminate (but much higher) number of escorts (frigates and destroyers), armed merchantmen, et cetera. Barely any grand cruisers*, iirc, and at most 5-6 battleships (offhand, I only recall the HDMS Cardinal Boras and the HDMS Divine Right for certain). I will search more thoroughly to find a confirmation or contradiction.

I feel, however, that I should point out that a Battle Fleet is a temporary organisation formed to fight a specific campaign/crusade. It doesn't really have any sort of fixed size, or even a pro-rated one based on the volume of Imperial-controlled space/number of planets comprising the theatre: it's whatever ships are present in theatre, and any that may be required if it escalates. It does normally comprise the sector fleet (or a part thereof) of and in which the conflict breaks out, and draws its name from that.

Sorry. My inner pedant insisted.

*Mostly because the Gothic Fleet didn't have any in service, and even the Gothic Reserve was noted to have at most a couple of Avenger/Exorcist class in mothballs that could be reactivated. The Cadian and Armageddon Fleets and Reserves, however, were noted as retaining more to play with. I guess it's a case of what was fashionable where, and what survived when fashions changed.

I don't think we're actually disagreeing that much, here. Your numbers for Battlefleet Gothic are pretty consistent with my view on Sector Battlefleet sizes: a handful of battleships, 50-60 capital ships and 150-200 other ships, mostly Frigates and Destroyers.

If I understand what you're saying correctly, you're saying that my numbers don't take account of the fact that Battlefleet Gothic at the time of the Gothic War was an unusual force, in that it was fighting a vast fleet action across the Sector...is that right? I guess I hadn't taken that into account...

I do think that there are permanently assigned vessels for each Imperial Sector, which are commonly called "Battlefleet [sector name]," but I accept that many "battlefleets" are likely to be scratch fleets formed to actually...er...battle, as opposed to simply patrol and police the space lanes. So I suppose we're talking about a distinction between Sector Fleets (Like Battlefleet Calixis) and actual Battlefleets , formed to defeat a military threat. Perhaps some confusion is creeping into the canon here in terminology? Battlefleet Gothic, as of the Gothic War, was a Battlefleet formed to do battle, which consisted of the Gothic Sector Fleet, plus whatever additional resources could be rushed into the Sector.

I guess, working this through in my mind, the implications of this are likely to be that Sector Fleets might be smaller in Sectors that are peaceful, perhaps with lighter and faster ships to fend off pirates, whereas Sector Fleets in contested or warzones might be larger, with more powerful ships.

To sum up a milion worlds Imperium is imho just a rhetorical figure just like a thousend year reich.

You know, that's kind of how I've always seen it, too! A rhetorical boast about the size of the Imperium, with no real idea as to the actual number.

As an aside, is anyone able to provide canon sources on the "Imperium of a million worlds" phrase and where this concept first appeared?

The thing I would be interested in seeing you calculate would be the total mass that the merchant fleet could trade between worlds regularly. If we know how many ships they have, and we have a decent idea of how big each ship is (the Vagabond for example), I'd be curious about how much stuff actually gets shipped between planets each year based on those numbers.

That's a big ask! I agree it would be nice to see some figures on this, but I wouldn't really know where to start!.

I guess extrapolating from my guesstimates, if there are 200-250 Navy vessels and 2000 or so merchant fleet vessels per sector, then this means about ten merchant ships for each planet. Assuming (the inherent danger of assuming anything always being the big problem here) that hive worlds, agri worlds and forge worlds get the lion's share of the traffic, that frontier worlds are only visited rarely, and that it takes "golden age of sail" scale timescales for ships to move between worlds, say 6 months to 2 years, then [taps furiously on calculator, draws complex diagrams on notepaper, moves sliderule across page, scowls, raises astrolabe to the heavens, screws up calculations, throws them away] I haven't got a clue where to start in working this out!

I'm pretty sure I've seen a reference to Battlefleet Gothic (that is, the Imperial Navy ships present to fight in the Gothic War, mostly from the Sector Fleet of the Gothic Sector, with some shortstopped on their way from elsewhere, some sent as back-up from other sectors, some pulled from a Reserve Fleet, and not counting any borrowed from other organisations, like the Mechanicum, the Inquisition, the League of Blackships, planetary governors' private fleets/SDF, Rogue Trader flotillas and the Astartes) at ~60 capital ships (that is, light cruiser or above), with an indeterminate (but much higher) number of escorts (frigates and destroyers), armed merchantmen, et cetera. Barely any grand cruisers*, iirc, and at most 5-6 battleships (offhand, I only recall the HDMS Cardinal Boras and the HDMS Divine Right for certain). I will search more thoroughly to find a confirmation or contradiction.

I feel, however, that I should point out that a Battle Fleet is a temporary organisation formed to fight a specific campaign/crusade. It doesn't really have any sort of fixed size, or even a pro-rated one based on the volume of Imperial-controlled space/number of planets comprising the theatre: it's whatever ships are present in theatre, and any that may be required if it escalates. It does normally comprise the sector fleet (or a part thereof) of and in which the conflict breaks out, and draws its name from that.

Sorry. My inner pedant insisted.

*Mostly because the Gothic Fleet didn't have any in service, and even the Gothic Reserve was noted to have at most a couple of Avenger/Exorcist class in mothballs that could be reactivated. The Cadian and Armageddon Fleets and Reserves, however, were noted as retaining more to play with. I guess it's a case of what was fashionable where, and what survived when fashions changed.

I don't think we're actually disagreeing that much, here. Your numbers for Battlefleet Gothic are pretty consistent with my view on Sector Battlefleet sizes: a handful of battleships, 50-60 capital ships and 150-200 other ships, mostly Frigates and Destroyers.

If I understand what you're saying correctly, you're saying that my numbers don't take account of the fact that Battlefleet Gothic at the time of the Gothic War was an unusual force, in that it was fighting a vast fleet action across the Sector...is that right? I guess I hadn't taken that into account...

I do think that there are permanently assigned vessels for each Imperial Sector, which are commonly called "Battlefleet [sector name]," but I accept that many "battlefleets" are likely to be scratch fleets formed to actually...er...battle, as opposed to simply patrol and police the space lanes. So I suppose we're talking about a distinction between Sector Fleets (Like Battlefleet Calixis) and actual Battlefleets , formed to defeat a military threat. Perhaps some confusion is creeping into the canon here in terminology? Battlefleet Gothic, as of the Gothic War, was a Battlefleet formed to do battle, which consisted of the Gothic Sector Fleet, plus whatever additional resources could be rushed into the Sector.

I guess, working this through in my mind, the implications of this are likely to be that Sector Fleets might be smaller in Sectors that are peaceful, perhaps with lighter and faster ships to fend off pirates, whereas Sector Fleets in contested or warzones might be larger, with more powerful ships.

True - but not every world is going to have a system defence force. Primitive feral or death worlds may well not have the resources to create such a local fleet, or even orbital defence platforms. Such fleets are less common than PDFs.

True, but I don't see how that in any way affects the calculations on how many navy vessels the Imperium posses.

Yes, it certainly affects how many are required, but that's not even remotely the same thing.

Primitive and Death Worlds may well find themselves undefended, because they cannot live up to what the imperium sees as their obligations.

And ofcourse the navy visits worlds every once in a while - some of them quite often is my guess - I hope I wasn't understood to argue differently

Does any one else think it seems a little ludicrous that the imperium would use space transport to bring food to hive worlds? Not because ships can't carry enough food. It just seems the warp is a little unstable.

I think space transport would be reserved for highly precious material such as nephium ad promethium which can't be found on most planets.

I figure hive worlds could have orbitals they use for agriculture. As well as recycling plants and algea plants.

May be they ship ust enough fertilizer to keep the on planet farms running rather than actual grain and meat.

Yeah, I actually agree with you (more or less) in terms of gross availability of hulls and crews (although I suspect there are far more hulls than there are officers and specialists to crew them, given the existence of the Reserve fleets). I was more quibbling over terminology. I guess it's like the arbites being used as a generic term for law enforcement, despite the fact that most of the organisations and persons so described are not members of the Adeptus Arbites. With that in mind (and while there is some extrapolation from canon - Passage Watch 27-Est for example - I must admit this is guesswork), a Battlefleet is not technically a Battlefleet unless set up to combat a specific threat, but any formation of warships may be colloquially referred to as a battlefleet, even if they technically have their own permanent designation.

I forgot about the reserve fleets! My thinking on reserve fleets is that they don't so much consist of ships that the Navy doesn't have crew for, (but that's a possibility) but to a greater degree consist of ships that are not economic or safe to operate except in cases of dire emergency. A lot of the Mid M35 "chaos cruiser" and grand cruiser patterns are heavily implied in a number of sources to be inherently flawed designs that tend to warp and corrupt their crews, and as such are not well regarded. Grand cruisers are only slightly more powerful than battlecruisers, but require disproportionately large crews to operate. Plus, reserve fleets in space don't operate like reserve fleets in the modern, planet bound world: spaceraft don't decay in a vacuum. They don't rust or fall apart. Kept in deep space reserve yards, they are effectively immortal. So it's probably more trouble to attempt to dismantle a ship than it is to just leave it sealed up in a naval yard for centuries.

er...so where was I going with this again? Sorry, got carried away... Ah yes. Ship numbers. I'd completely forgotten about reserve fleets. What do you think represents a reasonable size for a Sector reserve fleet? 10% of the size of the rest of the "active" fleet? 20%? Somewhere between those two sounds about right... so in the case of a 200 strong Sector Fleet, this would mean 20-40 mothballed ships of various classes, probably with a higher percentage of capital ships than the fleet proper... Any thoughts?

And I think that's a very good way to describe the naming convention of the Imperial Navy Sector fleets: "Colloquially known as battlefleets" even though they're not necessarily Battlefleets in the conventional sense of the term!

Does any one else think it seems a little ludicrous that the imperium would use space transport to bring food to hive worlds? Not because ships can't carry enough food. It just seems the warp is a little unstable.

I think space transport would be reserved for highly precious material such as nephium ad promethium which can't be found on most planets.

I figure hive worlds could have orbitals they use for agriculture. As well as recycling plants and algea plants.

May be they ship ust enough fertilizer to keep the on planet farms running rather than actual grain and meat.

I think you're right to a degree - warp travel is clearly very dangerous. However, the very existence of agri worlds is suggestive that they are necessary. While it is no doubt true that the Imperium possesses the technology to construct orbital farms, I can't recall seeing many references to such things. The world of Precipre is the only one that springs to mind that is similar.

I would hazard a guess that most of the risk of warp travel comes from travelling to unknown regions through parts of the warp that are inherently unstable. Travelling along well known warp conduits making tiny computer calculated jumps, in the manner of most of the chartist captains, is probably much less risky. I imagine a realtively stable command economy could be built around travel like this.

In terms of how most Hive worlds deal with food shortages, though, I reckon they eat dead people, ieatdeadpeople2. Corpse starch rations all the way!