In the Imperium, there are apparently two books of strategy: the Codex Astartes, and the Tactica Imperialis.

1. What are some of the key differences between the two "books"? Are there any, aside from the Codex apparently being more specific to the Space Marines?

2. What does the Tactica Imperialis have to offer that might prompt a Space Marine of a Codex Chapter to refer to it rather than the Codex?

3. Conversely, what would prompt an Imperial Guard or Imperial Navy officer to refer to the Codex Astartes? Do they even have access to it at all?

4. Whose treatises would be considered for inclusion in either book? Might something written by a "mere mortal" somehow make it into the Codex Astartes, and if so, would this be a relatively common or more like one-in-a-million? Obviously, for a Space Marine, having his treatise included in the Codex Astartes would be a major honor, but would it also be a great honor to be included in the Tactica Imperialis?

Anybody have any thoughts on the matter?

-Kirov

The Codex is written and done, more than likely not added to. Ever. The words of a Primarch > Everyone. I would say except the Emperor, but I'm pretty sure he's never written anything like that.

No one really knows what it written in the Codex except for Chapter organization.

I'm not even sure if anyone knows what is in the Tactica Imperialis, beyond general military strategy.

Given the reputation of the Codex, I wouldn't be surprised if an Imperial Guard officer had read it.

I'm not even sure if anyone knows what is in the Tactica Imperialis, beyond general military strategy.

A small excerpt of the Tactica Imperialis was written by Dan Abnett & Andy Hoare as a companion to the Tanith 1st & Only/Sabbat Worlds Crusade series. It's a collection of 4 different battles. They contain overall information, troop specifics (both Imperial and Hostile) and tactics of the encounters. From their format I would assume that the Tactica Imperialis is a huge collection of information about tactics, strategy, troop info and more. A type of Imperial Guard Wiki containing almost everything they know. And I would say that parts of the Codex Astartes (those used in combat) have been included to explain Space Marine tactics. Otherwise regimental S-3s (operations officers responsible for making up those spiffy battle plans) wouldn't be able to coordinate with astartes.

The problem with the codex astartes is that it is written with power armored demigods in mind and not footsloggers. A typical tactic that works for the marines wouldn't work for the IG. Sure reading it might be enlightening but it wouldn't help an officer trying to find a way to entrench a unit on a hill.

The Codex Astartes was written for the 'reformation' of the Imperium, post-Heresy. I believe it included the break up of the old Imperial Army into the current Guard and Navy as separate entities, so it certainly would have information useful to a mere mortal, though likely a bit highbrow for someone without an enhanced brain. I definately think of the Tactica as more of a living work, based on the events of recent/historical battles - so the two are very different, in their nature and accessability.

There are probably multiple volumes to the Tactica as well, something like a Big Encyclopedia of Killing Stuff or something.

Hmmm . . . upon a second look, it seems that "The wisdom of thousands of the Imperium's warriors has contributed to the codex" (Page 54, Deathwatch Core Rulebook) simply means that Roboute Guilliman incorporated the essays of other tacticians of the time into the codex rather than the codex being constantly added to like how it is with the Tactica Imperialis. My mistake.

Kirov said:

The Codex Astartes is a not only a summary/ collection of military treatise, it is also "guidelines" for Space Marines to conduct themselves. It also serves as guidelines for splitting up legions into chapters - the order to which a chapter is organised. This is to prevent one individual from amassing too much power such as Horus.

The way I have come to understand it, the Codex Astartes is entirely a Space Marine affair. It is unlikely that others would have access to it in general. As has been said, it's not just a book of strategy, but also a book defining how Space Marines are supposed to conduct themselves, their relation to the Emperor, information about geneseeds and likely lineages too, tactics, organization, limitations and laws and so on and so on.

Some Chapters disregard it entirely and are doing fine, unless you're listening to Matt Ward and his "spiritual liege" herp-derp.

The Tactica Imperialis, however, I imagine as being the definite book on strategy and tactics in the Imperium. Sort of an ever-expanding and built-upon Sun Tzu's Art of War for the stars, taught extensively in the Schola Progenium or any number of officer's schools and so on.

On top of that, I find it doubtful that these are the only two "Books of Strategy" in the Imperium. Even the Imperial Infantryman's Uplifting Primer could be considered a book of strategy or tactics in some regards. The Imperium is enormous, and I'd say that theoretical application of tactics and strategy is one of the few things you are likely to be allowed to apply any kind of scientific principle to.

Fgdsfg said:

...or maybe a result of Imperial stragery!

Partario said:

Actually, there is a third important book for space marines: the Imperial Fists' Book of Five Spheres'

1) The codex astartes was writen by the Ultramarine Primarch and serves as an all the rules you will ever need kind of book. The tome itself doesnt get altered but is often ignored/interpreted in interesting ways. The Tactica Imperium is according to the previous Imperial Guard Codex: "The Tactica Imperium is the most widespread manual employed by the Imperial Guard. It is not a single tome, however, and has no one author, instead it is a whole collection of documents, doctrines, manuals and notes approved for inclusion by the Departmento Munitorum and the office of the Lord Commander Militant of the Imperial Guard. he collection of books comprising the Tactica is therefore constantly being updated, often at a different pace, as the sheer size of the Imperium precludes any true standardisation.

2) It is unlikely that a chapter that follows the codex rigidly would ever look at the Tactica, however a more liberal chapter may at times study specific elements of the Tactica.

3) There is unlikely to be anything of worth in the Codex Astartes for a Guard officer as it has been written purely for space marines not for puny mortals.

Thye lack of cross understanding can and has caused problems in campiagns where the Space Marines forget that the Guard fighting alongside them are weak, squishy and cant keep going for days at a time.

4) The Codex has never been altered since it was written but different chapters may have other documents that they use for training/guidance and I imagine being included in that would be a great honour. A space marines work is unlikely to reach the Tactica due to the 2 organisations being completely separate but foir an officers work to be included in the Tactica would be a great honour.

Hope this helps

Ha, come to think of it, the IG probably aren't permitted to read the Codex, because given when it was written (immediately post-Heresy), it probably reads as an extremely Heretical document to the current era of non-Astartes; no references at all to a God-Emperor.

Wait a minute. I just realized that Lorgath Maclir, chapter master of the Storm Wardens, is a studier of the Tactica Imperialis. It is rumoured that he knows entire parts of the book by heart.

So, my conclusion, if the tactica imperialis is of such a interest to an adaptus astartes chapter master, then it does at least include some parts about space marines...

Watch-Captain Albus said:

Definitely. I don't think that the Codex Astartes is of any real interest to the Imperial Guard or the Imperial Navy and so forth, but there's no reason the Tactica Imperialis can't be of use to the Space Marines.

More than likely a very old version of the Tactica Imperialis would be contained within the Codex Astartes.

The Tactica, being a more fluid and evolving text, would still hold interest to Astartes strategists.

ItsUncertainWho said:

Yes, that is how I saw it too. The Codex Astartes has, in my opinion, plenty of information on the collaboration with the Imperial Army/Guard and the Imperial Navy, perhaps even on working together with Mechanicum forces (knight households, titan legions, tech guard, ...). The Tactica Imperialis just expands on these holy texts from Roboute Guilliman. But Only on the parts concerning non-Astartes, I think.

And for what concerns the "Book of Five Spheres." It says clearly in the Lexicanum that it was written as an Imperial Fists addendum to the Codex Astartes.

Fgdsfg said:

For one thing, the Imperial Guard and Imperial Navy did not exist at the time of writing it did they? Or at least the splitting of the Imperial Army into the Guard and Navy was only just taking place at the time (and Guilliman was instrumental in this) so both organisations may have changed so much that entries in the CA are not particularly relavant.

Where as the Tactica would pressumable contain the works of more recent Warmasters and Generals that made the most efficient use of cross organisational cooperation.

Face Eater said:

I think you are correct. There is this short story in Tales of Heresy in the Horus Heresy series where it is related how Guilliman is testing out the battle strategies and tactics of fighting against the other legions. After reading that story, I believe that Roboute Guilliman encoded all knowledge he had at that time. So, for me, the codex discusses force organisation, strategy, tactics, collaboration with other armed forces of the Empire, space marine discipline and conduct, command structure, uniform and much more. But all from the point of view of the Adeptus Astartes (or from the point of view of one of the greatest Primarchs of all time). Due to the mythic status Roboute Guilliman recieved later on and the extensive use of his codex as a guideline for the reorganisation of the space marines after the Horus Heresy, the codex is considered by many a holy text that should not be altered. And, on top of that, in the short story it was clearly said that Guilliman was writing the Codex to organise the Imperium for after the heresy.

The Tactica Imperialis is, in my eyes, a work that can contain some parts of the Codex Astartes, or can be read as an addendum of the Codex (if you are a space marine commander or something), but contains a lot more contemporary parts. The Tactica is a work that most Imperial Guard/Navy commanders, I think, have been adding parts to after campaigns or battles.

I see the TI as the supposed definitive treatise on strategy and tactics. But I also bet its multiple volumes contain contradictory info and tactics that have not been viable since the Heresy. Not to say its useless but any document that is constantly evolving is bound to have a more than a few problems.

I'd also put money down that every other sentence ends with "by execution."