Updating the Foundings Time Line

[Octavulg]

p 170 of the BRB 6e gives the Cursed Founding as 991.M35 (well, it goes horribly wrong then). Thus compressing things even further.

[Kurgan the Lurker]

Where does the "Third Founding on the first day of the new millenium" bit come from?

 

• 1st Chapter of the 3rd Founding, 001M32. Given the Chapter number 13 in place of one of the ‘treacher legions’. Incepted as a mobile Chapter based in a vast fighting fleet. WD97 pg. 39

[Octavulg]

Kurgan, have I told you lately how much I love you?

 

Thanks. ;)

 

I'll give it a little longer to see if any more dates fall out of the woodwork, and then I'll make a final version with accompanying essay that tries to explain the ... issues.

[Kurgan the Lurker]

As you can see, in regards to the Cursed Founding it is either support for the "a founding being spread out over time" or GW messed up the dates again:

 

 

 

• 598M35 – Founding, number unknown. Tiger Claws. Chapters Founded precisely for guarding the Maelstrom. C:CSMv3.5 pg. 7

• 021M31 – 2nd Founding. Largest Founding of Chapters. Codex Ultramarines pg. 10

• M36 -- 21st Founding, the Cursed Founding. Takes place immediately before the Age of Apostasy. Largest since the 2nd Founding. Chapters were beset by bad luck from the start with several disappearing while in action or warp space. Every surviving Chapter of the Founding is affected by spontaneous mutation of their gene-seed. As such the Chapters have gradually dwindled in size as their inability to raise and induct recruits means that battle casualties cannot be replaced. Codex: Ultramarines pg. 13

• 001M32 3rd Founding. WD97 pg32

• 26th Founding, 738m41. C:SMv3 inside back cover

• 991M35, The Cursed Fouding. Grey Knights called in to expunge the threat of many of the newly created Chapters. V6 rulebook pg. 170

[Octavulg]

I've added your info into my working document, Kurgan. I'll hammer out an 'official' table and a 'what actually makes sense' table shortly.

[Octavulg]

Questions about Foundings

When is a Chapter considered "founded"? Good question. It could be when they start growing the organs, when the organs are sanctioned as fit for use, or when the chapter's training cadre starts training new Marines. A small cadre of ten men training Scouts from scratch could produce a chapter in about forty years - but is that how it's done, or is recruitment initially conducted en masse to shore up the chapter's numbers?

 

It's remarkable how much we don't know about the process, really. In any case, I set out to make an official list which I would then fill in with estimated dates. Then I ran into a slight problem. See if you can spot it.

 

The Official List

021.M31 - Second Founding

001.M32 - Third Founding

888.M32 - Founding during the Astropath Wars

220.M33 - Howling Griffons founded

~500.M34 - Eighth Founding (mid M34)

~500.M35 - Tenth Founding (mid M35)

598.M35 - Tiger Claws founded

991.M35 - Twenty-First Founding

013.M36 - Thirteenth Founding

~555.M37 - Founding of the Dark Hunters

~999.M37/001.M38 - The Twenty-Third (Sentinel) Founding

~750.M40 - The Twenty-Fifth Founding

738.M41 - The Twenty-Sixth Founding

 

As you can see, there's a bit of a problem. The Tenth through Twenty-First foundings happen in the space of a millenium (while all others happen every five hundred years or so), and the Thirteenth happens after the Twenty-First. This is just stupid.

 

Thus, you get the Octavulg-Estimated version, where I ignore the minimum amount of things necessary to have things make sense:

Octavulg-Approved Founding Timeline

Founding Dates

2nd	021.M31	Date is given as 021.M31 in the Final Liberation Game Manual p 76 and in C:UM p 13. Seven years after the death of Horus (C:SM 5e p 14). The Legions are broken up and just over 400 chapters are created (C: GK, p 7).
3rd	001.M32	Founded on the first day of M32 per WD97 p 39.
4th	P: 888.M32	IA 10 p 114 suggests a founding during the Astropath Wars, which took place in 888.M32 (BRB 5e p 124).
5th	P: About 220.M33	220 or 221.M33 is the founding of the Howling Griffons (C:CSM 3e Rev, p 63). The number is not recorded. The Dark Angels geneseed was not used in this founding per C:DA v6 p 22.
6th	E: Mid-Late M33	The Dark Angels geneseed was not used in this founding per C:DA v6 p 22.
7th	E: Late M33/Early M34	If this founding was in M33, the Dark Angels geneseed would not have been used per C:DA v6 p 22.
8th	E: About 400.M34	Mid-M34 per IA 10, p 64. However, this will compress the next several foundings incredibly. Since this period is the Nova Terra Interregnum, it is possible that both the Ur-Council and the High Lords created legitimate foundings in this period, and that they were later renumbered.
9th	E: About 530.M34	-
10th	E: About 660.M34	IA 9, p 54 says mid-M35. This compresses the next eleven foundings into 500 years or less (vs. 3000 for the previous seven). This has thus been completely ignored.
11th	E: About 790.M34	-
12th	E: About 920.M34	-
13th	E: About 050.M35	This is the only founding for which the Adeptus Mechanicus does not possess original geneseed records (C:UM p 8). The Armageddon 3 Website included a communique from 013.M36 referring to the Exorcists as being in training following their founding. This has been ignored, because that would mean the 13th Founding within a century of the 21st, and I have limits. IA 10 p 124 seems to claim late M35/early M36, which carries the same problem. The highly-flawed IA: Emperor's Shield claims a founding date of M40 for the Exorcists, moving them out of the 13th Founding altogether. All of this has thus been ignored, since I refuse to have the 13th Founding within a century of the 21st (let alone AFTER it, as it might end up being)
14th	E: About 180.M35	-
15th	E: About 320.M35	-
16th	E: About 460.M35	-
17th	P: 598.M35	The Tiger Claws are founded at 598.M35 per C:CSM 3.5, p 7.
18th	E: About 700.M35	-
19th	E: About 800.M35	-
20th	E: About 900.M35	-
21st	991.M35 [/u]	991.M35 per BRB 6e, 170. "On the cusp of M36" (IA 9, p 106). Cursed Founding. Largest founding since the Second (C:UM p 13). Took place before the Age of Apostasy, which began within the first century or two of M36.
22nd	About 555.M37	The Dark Hunters are described as founded in the "dark days of the Occlusiad" (C:SM 5e, p 26). The Occlusiad War is from 550.M37 to 560.M37 (BRB 5e, 125). Their founding is not specifically mentioned, but there's only one option.
23rd	Late M37/Early M38	Late M37 per IA 9 p 74, Early M38 per IA 10 p 132. "The Sentinel Founding, created to aid the Imperium's defences in numerous ill-starred and vulnerable regions of the galaxy (IA 10, p 132)." "Generally believed to have been one of a series of linked foundings around this period designed to repair the power and reach of the Imperium's Space Marine forces which had suffered considerable losses in the preceding millenia."
24th	E: M39	-

25th M40, latter half Date per IA 9 p 94. Establishes chapter number 888 (WD 98 UK p 38). 26th738.M41Date is given as 021.M31 in the Final Liberation Game Manual, p 77 and in C:SM v3, IBC.

 

If you figure that a "Founding" happens when the chapters begin training marines, then these dates all work - some are close together, but there's still enough time for it to make sense (especially if you assume the Nova Terra Interregnum founded some Marine chapters).

[EzekyleVIII]

Does this mean the diy creation resources section will be altered? Having 400 chapters in the 2nd founding opens doors exponentially, though now I can find sensible founding for my wip...

This is an excellent piece of reference material, all compilers should be afforded many honours indeed

[Octavulg]

Does this mean the diy creation resources section will be altered?

Hopefully. I'll prod Olisredan or Messor into doing it at some point. That or just stick it in the Octaguide. Or both.

Having 400 chapters in the 2nd founding opens doors exponentially, though now I can find sensible founding for my wip...

It really does. That, and the Cursed Founding seems a lot bigger.

This is an excellent piece of reference material, all compilers should be afforded many honours indeed

Thanks. Me, Hrvat and Kurgan all found citations for stuff.

EDIT: Added the source for the Cursed Founding being the second-largest. I am the greatest of all 40K Internet resources, for I cite my damn sources.

[Reyner]

Nice work there Batman and well done to everyone who contributed - you should definately put this in the Octaguide and all the DIY refences and other guides. The 2nd Founding looks to be much better from a DIY point of view and makes sense for Guilliman (sp) to want to break up the Legions if there were enough marines left over to create 400 new Chapters. Now to think of the upcoming Iron Gauntlet - do I refine my existing Chapter or start an entirely new 21st Founding Chaper :D

[EzekyleVIII]

Just a thought, is subsidary info still the same, such as sallys being too small to split/ raven guard only being them and 2 others etc? Or in your researches is there conflicting fluff as regards the legions damaged at istvaan?

[Octavulg]

Reyner

It'll go in the Octaguide in time (I'll likely do a small update to the thing in a few weeks). The DIY Guide is up to Olisredan or Messor.

EDIT:

EzekyleVIII

Depends. Logically, all the Legions were bigger than their known Second Founding chapters would indicate. To what extent, I don't know.

Frankly, GW's made the fluff around that stuff more confusing, not less, and I wouldn't expect clarity any time soon.

[Messor]

So how complete are we feeling about this? It definitely needs a place in one or two DIY resources, and it looks solid as is, but I want to make sure you're done with it first.

 

Also, should anything be reconciled between the above and the time line here, slightly different from the first one which appears in the DIY resources.

[Octavulg]

So how complete are we feeling about this? It definitely needs a place in one or two DIY resources, and it looks solid as is, but I want to make sure you're done with it first.

I'm definitely done with it until the next Marine codex comes out (and likely beyond that). I've reviewed everything I know about that has relevant information.

So, basically, it's done until I find out it isn't.

Also, should anything be reconciled between the above and the time line here, slightly different from the first one which appears in the DIY resources.

Well, Ferrata said that one was basically entirely speculation. Mine's just mostly speculation. I kind of view mine as a total update of that one (a lot of information came out between then and now).

So, basically, replace that one with this.

We did an updated thing on the Black Crusades for the Legio Imprint, too. In fact, looking at that whole thing, it needs some updating.

*Sigh*

There is no rest for the wicked.

[Octavulg]

Proposed revised version of the article:

[color=#FFA500][b][size=4][font=Lucida Sans Unicode]The Foundings[/font][/size][/b][/color]

by [b]Octavulg[/b]

A Space Marine Founding is the process by which new Astartes chapters are created.  The High Lords command the Mechanicus to begin the process, geneseed is grown, training cadres are assigned...and then it all gets a bit murky.  


When is a Chapter considered "founded"? Good question. It could be when they start growing the organs, when the organs are sanctioned as fit for use, or when the chapter's training cadre starts training new Marines. A small cadre of ten men training Scouts from scratch could produce a chapter in about forty years - but is that how it's done, or is recruitment initially conducted en masse to shore up the chapter's numbers? 


It's remarkable how much we don't know about the process, really. In any case, I set out to make an official list which I would then fill in with estimated dates. Then I ran into a slight problem. See if you can spot it.


[b]The Official List[/b]

021.M31 - Second Founding

001.M32 - Third Founding

888.M32 - Founding during the Astropath Wars

220.M33 - Howling Griffons founded

~500.M34 - Eighth Founding (mid M34)

[b]~500.M35 - Tenth Founding (mid M35)[/b]

598.M35 - Tiger Claws founded

[b]991.M35 - Twenty-First Founding

013.M36 - Thirteenth Founding[/b]

~555.M37 - Founding of the Dark Hunters

~999.M37/001.M38 - The Twenty-Third (Sentinel) Founding

~750.M40 - The Twenty-Fifth Founding

738.M41 - The Twenty-Sixth Founding


As you can see, there's a bit of a problem. The Tenth through Twenty-First foundings happen in the space of a millenium (while all others happen every five hundred years or so), and the Thirteenth happens [i]after[/i] the Twenty-First. This is just stupid.


Thus, you get the Octavulg-Estimated version, where I ignore the minimum amount of things necessary to have things make sense:

[b]Octavulg-Approved Founding Timeline[/b]

[table=Founding Dates][th]Founding[/th][th]Date (E: Estimated, P: Possibly) [/th][th]Other Information[/th][tr][td=10%]2nd[/td][td=10%]021.M31[/td][td=30%] Date is given as 021.M31 in the Final Liberation Game Manual p 76 and in C:UM p 13. Seven years after the death of Horus (C:SM 5e p 14). The Legions are broken up and just over 400 chapters are created (C: GK, p 7). [/td][/tr][tr][td=10%]3rd[/td][td=10%]001.M32[/td][td=30%] Founded on the first day of M32 per WD97 p 39. [/td][/tr][tr][td=10%]4th[/td][td=10%] P: 888.M32 [/td][td=30%] IA 10 p 114 suggests a founding during the Astropath Wars, which took place in 888.M32 (BRB 5e p 124). [/td][/tr][tr][td=10%]5th[/td][td=10%]P: About 220.M33[/td][td=30%]220 or 221.M33 is the founding of the Howling Griffons (C:CSM 3e Rev, p 63). The number is not recorded. The Dark Angels geneseed was not used in this founding per C:DA v6 p 22. [/td][/tr][tr][td=10%]6th[/td][td=10%] E: Mid-Late M33 [/td][td=30%] The Dark Angels geneseed was not used in this founding per C:DA v6 p 22. [/td][/tr][tr][td=10%]7th[/td][td=10%] E: Late M33/Early M34 [/td][td=30%] If this founding was in M33, the Dark Angels geneseed would not have been used per C:DA v6 p 22. [/td][/tr][tr][td=10%]8th[/td][td=10%] E: About 400.M34 [/td][td=30%] Mid-M34 per IA 10, p 64. However, this will compress the next several foundings incredibly. Since this period is the Nova Terra Interregnum, it is possible that both the Ur-Council and the High Lords created legitimate foundings in this period, and that they were later renumbered.[/td][/tr][tr][td=10%]9th[/td][td=10%] E: About 530.M34 [/td][td=30%] - [/td][/tr][tr][td=10%]10th[/td][td=10%] E: About 660.M34 [/td][td=30%] IA 9, p 54 says mid-M35. This compresses the next eleven foundings into 500 years or less (vs. 3000 for the previous seven). This has thus been completely ignored. [/td][/tr][tr][td=10%]11th[/td][td=10%] E: About 790.M34 [/td][td=30%] - [/td][/tr][tr][td=10%]12th[/td][td=10%] E: About 920.M34 [/td][td=30%] -[/td][/tr][tr][td=10%]13th[/td][td=10%] E: About 050.M35 [/td][td=30%] This is the only founding for which the Adeptus Mechanicus does not possess original geneseed records (C:UM p 8). The Armageddon 3 Website included a communique from 013.M36 referring to the Exorcists as being in training following their founding. This has been ignored, because that would mean the 13th Founding within a century of the 21st, and I have limits. IA 10 p 124 seems to claim late M35/early M36, which carries the same problem. The highly-flawed IA: Emperor's Shield claims a founding date of M40 for the Exorcists, moving them out of the 13th Founding altogether. All of this has thus been ignored, since I refuse to have the 13th Founding within a century of the 21st (let alone AFTER it, as it might end up being)[/td][/tr][tr][td=10%]14th[/td][td=10%] E: About 180.M35 [/td][td=30%] - [/td][/tr][tr][td=10%]15th[/td][td=10%] E: About 320.M35 [/td][td=30%] - [/td][/tr][tr][td=10%]16th[/td][td=10%] E: About 460.M35 [/td][td=30%] - [/td][/tr][tr][td=10%]17th[/td][td=10%] P: 598.M35 [/td][td=30%] The Tiger Claws are founded at 598.M35 per C:CSM 3.5, p 7. [/td][/tr][tr][td=10%]18th[/td][td=10%] E: About 700.M35 [/td][td=30%] -[/td][/tr][tr][td=10%]19th[/td][td=10%] E: About 800.M35 [/td][td=30%] - [/td][/tr][tr][td=10%]20th[/td][td=10%] E: About 900.M35 [/td][td=30%] -[/td][/tr][tr][td=10%]21st[/td][td=10%] 991.M35 [/u][/td][td=30%] 991.M35 per BRB 6e, 170. "On the cusp of M36" (IA 9, p 106). Cursed Founding. Largest founding since the Second (C:UM p 13). Took place before the Age of Apostasy, which began within the first century or two of M36.[/td][/tr][tr][td=10%]22nd[/td][td=10%] About 555.M37 [/td][td=30%] The Dark Hunters are described as founded in the "dark days of the Occlusiad" (C:SM 5e, p 26). The Occlusiad War is from 550.M37 to 560.M37 (BRB 5e, 125). Their founding is not specifically mentioned, but there's only one option. [/td][/tr][tr][td=10%]23rd[/td][td=10%]Late M37/Early M38[/td][td=30%] Late M37 per IA 9 p 74, Early M38 per IA 10 p 132. "The Sentinel Founding, created to aid the Imperium's defences in numerous ill-starred and vulnerable regions of the galaxy (IA 10, p 132)." "Generally believed to have been one of a series of linked foundings around this period designed to repair the power and reach of the Imperium's Space Marine forces which had suffered considerable losses in the preceding millenia."[/td][/tr][tr][td=10%]24th[/td][td=10%] E: M39 [/td][td=30%] - [/td][/tr]

[tr][td=10%]25th[/td][td=10%] M40, latter half [/td][td=30%] Date per IA 9 p 94. Establishes chapter number 888 (WD 98 UK p 38). [/td][/tr][tr][td=10%]26th[/td][td=10%]738.M41[/td][td=30%]Date is given as 021.M31 in the Final Liberation Game Manual, p 77 and in C:SM v3, IBC.[/td][/tr][/table]


If you figure that a "Founding" happens when the chapters begin training marines, then these dates all work - some are close together, but there's still enough time for it to make sense (especially if you assume the Nova Terra Interregnum founded some Marine chapters).


As to how long it would take a chapter to get up to strength: the latest the Black Carapace can apparently be implanted is 18 years. The earliest you can start implanting organs is 10. So figure five or six years to train a Scout.


Next: how big's a training cadre? I'd expect two of each specialist, two command officers and four sergeants as a minimum. Perhaps one or two extra Sergeants. The chapter will also start with 1000 men worth of geneseed implants. It could be a lot more, of course - anything up to a company worth of men would make at least some degree of sense. But I'll go with a small cadre just for demonstration purposes.


There are a couple of ways things could go from here. The way I think it'd work (spoilered for length): 

[spoiler]

Initially, there are six officers (four sergeants, the First Captain and the Chapter Master). The Chapter Master serves as Scout Captain, the First Captain serves as senior Scout Sergeant, and the other four serve as Scout Sergeants. They thus train 54 Scouts.


Assume Scouts take 20% casualties in training in a five year period (likely high) and that ordinary Marines take 10% casualties (that 3+ save and some experience makes a world of difference). I count Scout Sergeants as Marines here. Note that practically speaking, this would happen gradually over the five year period.


You lose one Sergeant and 11 Scouts. Two Senior Officers, three Sergeants, 43 Marines remain. One Senior Officer takes 39 of the Marines and forms the First Company (40 Marines). The best four Scouts become Scout Sergeants (for a total of seven). The Scout Company can now take 72 recruits.


In the next five years, you lose four Marines and 14 Scouts. The First Company now has 89 Marines and one Senior Officer, and you promote an additional three Scout Sergeants for a total of one Senior Officer and 10 Scout Sergeants in the Scout Company. You take 100 recruits. So in just ten years, your Scout Company is over full strength and you've almost got a Battle Company.


Now, there are two possibilities. If the Chapter has a small home world and doesn't recruit outside it, that may be the maximum limit of how many recruits can be taken each year. However, with a larger home world, the Scout Company can keep growing until the Chapter is at full strength.


In the next five years, you lose 9 Marines, one Scout Sergeant and 18 Scouts, graduating 82. 9 go to the First Company, bringing it back to 90 Marines. 70 go to the Second Company. Three become Scout Sergeants (practically, they're promoted from the First and replaced). You have 12 Scout Sergeants and a Senior Officer in the Scout Company (who I'll count as a Scout Sergeant after this). You take 117 recruits, and almost have two Battle Companies after just fifteen years.


In the five years after this, you lose 16 Marines, one Scout Sergeant and 23 Scouts, graduating 94. 16 bring the companies up to strength, and 70 go to creating the Third Company (90/70/70). That leaves 8 to create Scout Sergeants. The Scout Company is now at double strength, with 20 Scout Sergeants. You take 180 recruits, and have about two and a half Battle Companies (plus lots of extra Scouts) after 20 years.


In the five years after this, you lose 25 Marines, two Scout Sergeants and 18 Scouts, graduating 162. 27 bring formations back up to strength, leaving 135. 40 bring the Second and Third up to 90 men each. 90 form the Fourth Company. The last five serve as Scout Sergeants (25 total). 225 recruits, 25 years.


Five years later, you lose 36 Marines, three Scout Sergeants and 23 Scouts, graduating 202. 39 bring formations up to strength, leaving 163. 90 form the Fifth, 60 form the Sixth, and the last three become Scout Sergeants (28). 252 recruits, 30 years.


Five years after this, you lose 42 Marines, three Scout Sergeants, and 25 Scouts, graduating 227. 45 bring formations up to strength, leaving 182. 30 go to the Sixth, 90 go to the Seventh, 60 go to the Eighth. Two become Scout Sergeants (30). 270 recruits, 35 years.


Five years after this, you lose 69 Marines, three Scout Sergeants and 27 Scouts, graduating 243. 72 bring formations up to strength, 30 bring the Eighth up to 90, and 90 more create the Ninth. This leaves 71. If you take twenty Scout Sergeants out of the Scout Company, you bring every company to full strength and have a full strength Scout Company after a mere forty years.

[/spoiler]


Plausible enough math would suggest that it'd take you a mere 25 years to have four Battle Companies at nearly full strength, and only forty to reach full Chapter strength. And that's with a fairly small training cadre of less than twenty Marines, who receive no other assistance beyond the 1000 progenoids at the start. 

In the long run, this should all probable turn into Librarium articles.

[Messor]

Fantastic, thanks for getting this together. I'll get it put up today!

[Octavulg]

I'm going to start updating the big timeline as well, I think. It needs it.

[Messor]

Questions about Foundings

 

The Official List

021.M31 - Second Founding

001.M32 - Third Founding

888.M32 - Founding during the Astropath Wars

220.M33 - Howling Griffons founded

~500.M34 - Eighth Founding (mid M34)

~500.M35 - Tenth Founding (mid M35)

598.M35 - Tiger Claws founded

991.M35 - Twenty-First Founding

013.M36 - Thirteenth Founding

~555.M37 - Founding of the Dark Hunters

~999.M37/001.M38 - The Twenty-Third (Sentinel) Founding

~750.M40 - The Twenty-Fifth Founding

738.M41 - The Twenty-Sixth Founding

 

As you can see, there's a bit of a problem. The Tenth through Twenty-First foundings happen in the space of a millenium (while all others happen every five hundred years or so), and the Thirteenth happens after the Twenty-First. This is just stupid.

 

Thus, you get the Octavulg-Estimated version, where I ignore the minimum amount of things necessary to have things make sense:

Octavulg-Approved Founding Timeline

Founding Dates

2nd	021.M31	Date is given as 021.M31 in the Final Liberation Game Manual p 76 and in C:UM p 13. Seven years after the death of Horus (C:SM 5e p 14). The Legions are broken up and just over 400 chapters are created (C: GK, p 7).
3rd	001.M32	Founded on the first day of M32 per WD97 p 39.
4th	P: 888.M32	IA 10 p 114 suggests a founding during the Astropath Wars, which took place in 888.M32 (BRB 5e p 124).
5th	P: About 220.M33	220 or 221.M33 is the founding of the Howling Griffons (C:CSM 3e Rev, p 63). The number is not recorded. The Dark Angels geneseed was not used in this founding per C:DA v6 p 22.
6th	E: Mid-Late M33	The Dark Angels geneseed was not used in this founding per C:DA v6 p 22.
7th	E: Late M33/Early M34	If this founding was in M33, the Dark Angels geneseed would not have been used per C:DA v6 p 22.
8th	E: About 400.M34	Mid-M34 per IA 10, p 64. However, this will compress the next several foundings incredibly. Since this period is the Nova Terra Interregnum, it is possible that both the Ur-Council and the High Lords created legitimate foundings in this period, and that they were later renumbered.
9th	E: About 530.M34	-
10th	E: About 660.M34	IA 9, p 54 says mid-M35. This compresses the next eleven foundings into 500 years or less (vs. 3000 for the previous seven). This has thus been completely ignored.
11th	E: About 790.M34	-
12th	E: About 920.M34	-
13th	E: About 050.M35	This is the only founding for which the Adeptus Mechanicus does not possess original geneseed records (C:UM p 8). The Armageddon 3 Website included a communique from 013.M36 referring to the Exorcists as being in training following their founding. This has been ignored, because that would mean the 13th Founding within a century of the 21st, and I have limits. IA 10 p 124 seems to claim late M35/early M36, which carries the same problem. The highly-flawed IA: Emperor's Shield claims a founding date of M40 for the Exorcists, moving them out of the 13th Founding altogether. All of this has thus been ignored, since I refuse to have the 13th Founding within a century of the 21st (let alone AFTER it, as it might end up being)
14th	E: About 180.M35	-
15th	E: About 320.M35	-
16th	E: About 460.M35	-
17th	P: 598.M35	The Tiger Claws are founded at 598.M35 per C:CSM 3.5, p 7.
18th	E: About 700.M35	-
19th	E: About 800.M35	-
20th	E: About 900.M35	-
21st	991.M35 [/u]	991.M35 per BRB 6e, 170. "On the cusp of M36" (IA 9, p 106). Cursed Founding. Largest founding since the Second (C:UM p 13). Took place before the Age of Apostasy, which began within the first century or two of M36.
22nd	About 555.M37	The Dark Hunters are described as founded in the "dark days of the Occlusiad" (C:SM 5e, p 26). The Occlusiad War is from 550.M37 to 560.M37 (BRB 5e, 125). Their founding is not specifically mentioned, but there's only one option.
23rd	Late M37/Early M38	Late M37 per IA 9 p 74, Early M38 per IA 10 p 132. "The Sentinel Founding, created to aid the Imperium's defences in numerous ill-starred and vulnerable regions of the galaxy (IA 10, p 132)." "Generally believed to have been one of a series of linked foundings around this period designed to repair the power and reach of the Imperium's Space Marine forces which had suffered considerable losses in the preceding millenia."
24th	E: M39	-

25th M40, latter half Date per IA 9 p 94. Establishes chapter number 888 (WD 98 UK p 38). 26th738.M41Date is given as 021.M31 in the Final Liberation Game Manual, p 77 and in C:SM v3, IBC.