League of Heraklion

[Volt]

LEAGUE OF HERAKLION

CHAPTER NAME: ..............THE LEAGUE OF HERAKLION FOUNDING: ..................UNKNOWN, 245.M33 CHAPTER WORLD: .............THRAKION FORTRESS MONASTERY: ........BULWARK OF MARCIAN GENE-SEED (PREDECESSOR): ...LEGIO XIII KNOWN DESCENDANTS: .........NONE "Victory in war shall never be truly achieved by the pitched field. In order to warrant your foe's vanquishing they must be harried invariably. Permit them no respite, slash at their supple holdings and above all else sow terror in their ranks. Only then might you engage in vain pursuit of glory upon the field in battle; yet if you have acquitted yourself with vigilance you shall discover your foe already routed."

T

he League of Heraklion was born from the tattered remnants of the Ultramarines Third Company in M33 during the Company's prosecution of a minor Ork WAAAGH! centered on the world of Thrakion. Initially the campaign had been progressing well for Captain Camillus of the Ultramarines' Third Company - the Orks were hammered in multiple set piece battles in the Thrakion badlands that saw the greenskins rout into the highlands. However Camillus was consumed by pride in these victories and, believing total victory imminent, threw the entire company upon the Orks with the intention of severing the Warboss' neck personally. After Camillus had committed the company in its entirety to the ground war the rest of the Ork WAAAGH! burst from the warp. The third company fleet was forced to evacuate the system to avoid destruction, leaving Camillus and his men stranded on the planet while the company flotilla sought to hail reinforcements from the rest of the chapter. 
 
Camillus recognized the desperate situation and threw himself upon the Warboss, but to no avail. Inferior in martial capability to the creature the Captain succeeded solely in seeing his form torn asunder by the monster's power klaw. The field lost, Third Company routed and reorganized at some distance from the Ork position. It was then a marine by the name of Heraclius took charge of the situation, a company veteran and member of the Captain's Command Squad, Heraclius was already an experienced marine - but otherwise considered unremarkable by his brothers for being anything more than a simple brute. Much to their surprise, Heraclius proved himself above and beyond a creature of brawn, possessing a tactical mind keen to strip apart the Orks piecemeal. He reorganized the entirety the surviving members of Third Company into kill teams and dispatched them on lightning raids to sabotage the enemy's logistics. Avoiding pitched fights entirely, Third Company remained on the move for the better part of a year, dodging the Orks whenever a confrontation was attempted.
 
A year of fighting in to the campaign, and Heraclius had managed to miraculous steer the company from destruction. The Orks, being harried endlessly by Astartes raiders and allowed no peace, grew careless - while the Warboss became infuriated with his stymied WAAAGH!. Heraclius drew a plan to finally sever the head of the foul creature, a decisive strike to finally cripple the WAAAGH! and sow chaos amongst the ranks of greenskins by plunging them into anarchy. To this end Heraclius elected to bring the best of his men and his greatest companions, a larger than usual force with the intention of smashing any trace of resistance. They committed themselves to the assault, rushing into battle to attract the ire of the green horde and mask their intentions from the keen mind of the Warboss. The third sold themselves dearly as many brothers fell before Heraclius called for the feigned retreat. The Ultramarines rushed behind the marked ground of the hills and waited until over half of the ork force crested the badlands before detonating the charges laid underground.
 
A terrific line of shaped charges detonated and clove through the orks, cutting off the Warboss from the rest of his army and annihilating most of his elite retinue in one fell blow. Immediately the remnants of third company beset the bewildered orks, with Heraclius singling out the beast for a personal clash of arms. Wracked by the loss of so many astartes and Thrakions he came to care for, he met the warboss with unhinged brutality. To his blows there was no degree of refinement, no aspect of the faux-nobility flaunted by so many sons of Macragge. He met the warboss as an equal; a feral animal snarling with unbridled rage that tore into its foe with tooth and claw. So great was the fury behind Heraclius' blows that his prized maul was reduced to a broken shaft of metal, and so the astartes restored to his fists to finish the monster. When the fighting ended the horde of greenskins that lay behind the small canyon gouged by the glut of explosives beheld the severed head of their leader and were put to rout.
 
Shortly thereafter the battle, the Ork invasion of Thrakion ground to a halt as infighting consumed the entirety of the WAAAGH!, the greenskin presence beginning to disintegrate as they butchered their own number. The remnants of Third Company were finally relieved by the arrival of the Ultramarines First, Second, and Sixth Companies - finding only a paltry number of brothers left alive out of the original 110 men. Concluding that Third Company was lost due to the casualties it has sustained, and seeing fit to honor their brother for seizing victory in the direst circumstances, the Ultramarines petitioned the High Lords to establish another Chapter. The responding edict took decades to arrive, but for more cynical reasons the High Lords permitted Heraclius and his retinue to proceed in a new founding. For the High Lords the logic behind the desicion was obvious - Heraclius may have thwarted a minor WAAAGH!, but the greenskin population itself was not destroyed. Coupled with neighboring polities of minor xenos located in the galactic north-east, bolstering the defenses with a thousand more astartes was merely common sense.
 
The initial years of the Chapter were a rocky start as the League of Heraklion was founded by only a handful of astartes with no further volunteers from other companies to aid in the founding. It took decades to bring the chapter up to a quarter strength, and it was only after a century of relentless recruitment coupled with support from the Adeptus Mechanicus that the League was able to bring its ranks up to a thousand strong. Interestingly this fresh wave of mass recruitment meant that few members of the Chapter actually held any connection to the culture and traditions of the Ultramarines - they were a virginal crop of recruits, devoid of combat experience and ripe for molding by their new Chapter Master. There were dangers however that Heraclius and his Captains had to avoid - namely that none of them had gone through the traditional means of acquiring their ranks. The first ten captains of the League of Heraklion were drawn not from hardened first company members - but the rank and file survivors of Third Company from the Thrakion defense.

Their first combat engagement involved putting down the Cult of the Bloodied Psalter, an insurgency in the Nidum Subsector, in assistance of the local Forge World. Heraclius met the enemy with unrelenting violence, establishing a trend for the chapter under his control. Little heed was paid for collateral damage inflicted by the Chapter as it prosecuted an unceasing war that lasted for three months. Under the direction of the young Chapter Master the League was organized into dual-company strike teams which were deployed without relief for two weeks. They would only conclude their operations when the brothers were exhausted beyond the point of combat effectiveness, cycling to the next two companies. These companies were in turn split into kill teams which used thunderhawks for transport between missions; their increased mobility allowing them to overwhelm the enemy without warning before moving on to the next target. Supply lines were ruined, enemy command structures decapitated, and industrial sites annihilated under the Chapter's discretion.
 
By its conclusion the industrial production of the three main worlds that saw campaigning were ruined by the Chapter for decades. Although grateful for the swift response and decisive fighting, the Magos of Nidum found himself nonplussed and never asked for the League's assistance again. Further campaigns under the leadership of Heraclius followed a similar pattern - devastating the enemy with persistent and rapid skirmishing that ensured minimal casualties for the chapter at the cost of immense collateral damage to the planets "aided". It was not long until the rage of Heraclius and brutal nature of the League of Heraklion was infamous throughout the galactic north-east - a trait not entirely positive for the Chapter's well being. Although they had the respect of their fellow Ultramarines for their success in war, such respect was not shared by neighboring polities. The Adeptus Mechanicus and the Departmento Munitorum in particular considered the arrival of the League a bane, for the wake of the League often meant headaches and years of rebuilding. The terror, as some neighboring sectors called the era, would end with Heraclius' death in the First True War of Veonid where he succumbed to injuries sustained in combat with a Bloodthirster.
 
With the death of its first Chapter Master a confused period of debate erupted within the League as to how succession would be handled. Unlike many other chapters the League of Heraklion was largely comprised of its original members, as their focus on reducing astartes casualties and skirmishing meant their attrition rates were unusually low. With a glut of old and experienced marines there was a surplus of potential replacements for Heraclius - over fifteen according to Librarius records. Eventually the captains of the League elected to form a new governing body, the Synkletos. A governing body consisting of every member of the chapter, the Synkletos would deliberate on military intervention, supply contracts with the Adeptus Mechanicus, and any other minutia of the chapter's life outside of the immediate concerns of battle. While each brother would have a vote in this body, for experience's sake each specialist and officer would have a weighted vote increasing in potency according to their position, with the chapter master (hailed as Strategos in the chapter's adopted native tongue) holding the most. In this manner the League hoped to create a system that would both ward them from corruption, and allow them to counter the actions of an especially brash chapter master in the future.
 
<<Then there are one or more paragraphs concerning the Chapter's combat doctrine, including how much or how little the Chapter adheres to the Codex Astartes and how it views that tome.>>

<<Then comes information about the Chapter's homeworld, fortress monastery, and fleet.>>

<<Then comes additional information on the Chapter and things that differentiate it from other Chapters.>>

League of Heraklion 4th Company
Like most Brothers of the League

Ioannes adorns a hybrid suit with

bonding studs, suiting the modular

nature of the chapter's doctrine

Legeonarios Ioannes

League of Heraklion 1st Company

Theodoros is a legend amongst his squad

and veteran of countless campaigns. Most

recently he served in the boarding actions

against renegade astartes attempting to raid

Forge World Incaladion in wake of the

devastation sown by the Thousand Sons

Oikeios Theodoros

Use the Space Marine Painter without weapons to create the images>>

ORGANIZATION
<<A paragraph or two on the Chapter's organization (short paragraph if Codex-adherent, longer if the Chapter has some degree of deviation)>>

<<Paragraphs to describe the key distinguishing characteristics of the Chapter>>

<<Paragraph to describe the Chapter’s fleet and combat organizations>>

<<Paragraph to describe the Chapter’s heraldry and appearance>>

SELECTED BATTLE HONORS <<include 1-3 of these>>
<<Battle/Operation/Campaign Name>> [###.M##]
<<A few paragraphs to describe the battle/operation/campaign and why it was notable for the Chapter>>

<<Battle/Operation/Campaign Name>> [###.M##]
<<A few paragraphs to describe the battle/operation/campaign and why it was notable for the Chapter>>

<<Battle/Operation/Campaign Name>> [###.M##]
<<A few paragraphs to describe the battle/operation/campaign and why it was notable for the Chapter>>

COMBAT SQUAD <<SQUAD NAME>>
<<#>><<RD/ST/TH>> <<BATTLE/RESERVE>> COMPANY

[/captionleft]

[/captionright]

Veteran Sergeant <<(or other title)>> <<Sergeant's name>> Commander <<Tactical/Assault/Devastator/Scout>> Squad <<Sergeant’s name>> <<#>><<rd/st/th>> <<Battle/Reserve>> Company <<Chapter Name>> <<A few lines of information (make sure you hard return each line)>>

<<Chapter Name>> Chapter Icon Common Armorial Use

[captionleft=Brother <<(or other title)>> <<Battle-brother’s name>> <<A few lines of information (make sure you hard return each line)>>]

Brother <<(or other title)>> <<Battle-brother's name>> <<A few lines of information (make sure you hard return each line)>>

[captionright=Brother <<(or other title)>> <<Battle-brother's name>> <<A few lines of information (make sure you hard return each line)>>]

Brother <<(or other title)>> <<Battle-brother's name>> <<A few lines of information (make sure you hard return each line)>>

Edited May 13, 2020 by Volt

[Brother Lunkhead]

Well...… you've got my attention Brother Volt This is an interesting start and I eagerly wait to see how your chapter's story develops.

[Volt]

Reserving this post for a gallery as I forgot to do it earlier. Also redid the initial paragraphs and added some more. Still WIP.

GALLERY

 

Oikeios Ioannes

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

>

Edited April 20, 2020 by Volt

[Bjorn Firewalker]

I like your story of the Chapter's founding, though I doubt the Ultramarines Chapter Master would tolerate Heraclius' apparent insubordination, when the latter refused to return to the Ultramarines and rebuild the 3rd Company. Maybe have Heraclius argue the Ultramarines 3rd Company should be permanently detached to Thrakion, to defend the planet, while the Ultramarines decide it's more efficient and effective to simply petition the High Lords of Terra to found a new Chapter there?

[Brother Lunkhead]

Very fine story and an excellent start. I echo Brother Bjorn's concern on the founding. I'm afraid that would be tantamount to treason, and the 3rd would be declared renegade, and you know where that ends. Bjorn's idea sounds very plausible.

[Volt]

I like your story of the Chapter's founding, though I doubt the Ultramarines Chapter Master would tolerate Heraclius' apparent insubordination, when the latter refused to return to the Ultramarines and rebuild the 3rd Company. Maybe have Heraclius argue the Ultramarines 3rd Company should be permanently detached to Thrakion, to defend the planet, while the Ultramarines decide it's more efficient and effective to simply petition the High Lords of Terra to found a new Chapter there?

The tricky thing is that I actually have no idea how the M33 foundings worked. Chronologically they would be close cousins to the Howling Griffons in founding dates, but i have no idea how that actually got started or the official mechanisms of how for it to occur.

 

Also although I haven't got to the point yet, the League of Heraklion will be very unique when it comes to organization. Structurally they will consist of 1000 linemen, with no scout company, instead 10 scouts are attached to each company as recon teams preparing a planet for a planetstrike campaign. But the Chapter does not use ground vehicles, almost at all. They still have an armory of rhinos, land raiders, etc from their founding, but it's all mothballed on ships.

 

Everybody uses Storm Eagles, and circa M41 is switching slowly over to Stormravens. Each company is thus split into 20 man teams of two squads, which hop around the planet via aircraft to strike at critical targets before leapfrogging to the next zone. They don't due attrition campaigns, bother holding ground, or engage in pitched battles. Instead they focus on knocking out anything important that the enemy leaves somewhat exposed before immediately redeploying elsewhere. So if they were to come across a Warband of Black Legionaries, they would never face the Chaos Marines fairly in the field. Rather they target fuel and ammunition depots, ambush convoys, capture enemies to interrogate, use said intel to whack VIP's in the enemy command structure, destroy generators/power grids, create landslides, etc to harry the enemy for a period of 300 hours without cessation. Then the combat teams stand down and are cycled to the next company, rinsing and repeating until the enemy is reduced to a disorganized rabble that is finally annihilated with an overwhelming show of force.

[gripschi]

Maybe you use the 4th Founding? It is a time after the War of the Beast, which battered many Chapters.

 

The perfect Excuse to get rid of problematic Personal. It was after all a huge Founding.

[Brother Lunkhead]

The problem is that based on the current storyline, the 3rd are not just "problematic personnel". They would be considered renegade, especially by a codex lovin' Chapter like the Ultramarines. If a unit was to be recommended as the core for a new founding, they would have to be loyal and exceptional in every way in the eyes of the Ultramarines.

 

As far as foundings go, most are initiated by the High Lords of Terra based on a perceived need. Chapters then forward personnel. Since not a lot has been set down in the lore as far as detail concerning Chapter founding, you still have a lot of wiggle room. In the end though, it does have to be approved by the High Lords.

 

Now, it's your Chapter and you're free to proceed as you see fit. I'm just pointing out the boundaries of the lore.

Edited April 23, 2020 by Brother Lunkhead

[Bjorn Firewalker]

Also although I haven't got to the point yet, the League of Heraklion will be very unique when it comes to organization.

A unique, NOT CODEX COMPLIANT organization is NOT characteristic of the Ultramarines and their descendants. Maybe claim the League is an Imperial Fists descendant instead?

Structurally they will consist of 1000 linemen, with no scout company, instead 10 scouts are attached to each company as recon teams preparing a planet for a planetstrike campaign.

Codex Chapters use Scout Companies to train new recruits. If the League has no Scout Companie, does this mean each Company recruits and trains new Marines on its own? That the League consists of nine Companies with 111-112 Marines each?

But the Chapter does not use ground vehicles, almost at all.

This a stupid limitation. Flyers are NOT stealthy during atmospheric reentry, i.e., while transporting Marines from their starships to planetside battlefields; additionally, inclement weather and enemy air defense may prevent flyers from being used at all, as they do in real life.

 

Ground vehicles thus grant the League the ability to transport troops with relative speed (faster than walking, anyways) and stealth (stealthier than a flyer thundering and lighting up the sky during atmospheric reentry, anyways), as well as serving as platforms for Whirlwind missile launchers and other ordnance- the latter of which is CRITICAL to suppressing enemy fire so your Marines may live to storm enemy lines.

They don't due attrition campaigns, bother holding ground, or engage in pitched battles.

So they have no way of enduring a siege? What do they do if the Red Corsairs attack the League's fortress-monastery in order to seize its gene-seed? If an Ork warband attacks an arms manufactory with the intention of using it to make all its members "Flash Gitz," will the League simply retreat and allow the foul xenos to drown the planet in shot, or destroy it to deny the xenos- pissing off the AdMech, and denying the Imperium arms the Emperor needs to defend His realm?

 

You have good ideas, but you need to think on the long-term consequences of implementing them.

[Brother Lunkhead]

Brother Bjorn makes some excellent observations. You should definitely give them due consideration.

 

I think overall your Chapter is not inconsistent with other Ultramarine foundings. The Mortifactors at a glance don't seem to fit the mold. The Iron Snakes diverge significantly in their organizational structure from their founding Chapter. But these divergent characteristics probably evolved over time to meet circumstances unique to each Chapter. Perhaps Heraclius was one of those more flexibly minded Ultramarines who followed in the footsteps of Aeonid Thiel.

 

While attrition warfare is certainly not the Space Marines preferred method of warfare, they should be prepared to wage it. Your combat doctrine is basicly sound. It just needs to be more flexible.

 

I understand your favor for flyers as transport. They fit well with your doctrine. However , there will be instances where ground transport will be preferred. Take advantage of all of your resources.

 

I like what you have here, but as Bjorn suggests, think in terms of the big picture. I look forward to seeing more.

Edited April 23, 2020 by Brother Lunkhead

[Brother Cambrius]

So this is certainly a good fresh idea to build on, Volt! (and I absolutely love the colour scheme and symbols too! Silver and purple work oh so well.  )

Bjorn left some pretty good feedback on this which I'm going to add to with some ideas or suggestions too to help you along. :)

 

 

Also although I haven't got to the point yet, the League of Heraklion will be very unique when it comes to organization.

A unique, NOT CODEX COMPLIANT organization is NOT characteristic of the Ultramarines and their descendants. Maybe claim the League is an Imperial Fists descendant instead?

 

 

Not sure if the capslock was necessary there to get the point across.

 

True enough it would be a bit of an outlier in terms of breaking the Codex Astartes, especially within the time frames of the splitting of the Legions being in relatively recent memory. But in this particular case, it's almost a nature vs nurture situation where the nature of combat and the events that befell the 3rd Company's elements have drastically altered their combat styles and organisation for the sake of survival and exacting the Emperor's will.

 

Atop that, there are some UM descendants that have altered drastically in their beliefs and combat style over the years, the Mortifactors are a good example and I believe are a 2nd Founding Chapter, so divergences can happen amongst the UM descendants.

 

In a compromise, you could possibly go down the route of not having Heraklion being insubordinate to the Ultramarine Chapter Master, he was his commander after all prior to the events on Thrakion, so respect will be there. Instead, Heraklion and the new/surviving command staff petition the Chapter Master to allow the survivors of the Third Company to break away as their combat styles etc have become too divergent to ever truly fit back into the Ultramarines and the region they are in badly needs protection.

 

If this coincided with the Fourth Founding, it would be an apt possibility the Ultramarines then petition for the Sons of Heraklion to be regarded as a new Chapter, as the former Legion would certainly hold some clout in ensuring the High Lords of Terra permit it.

 

Structurally they will consist of 1000 linemen, with no scout company, instead 10 scouts are attached to each company as recon teams preparing a planet for a planetstrike campaign.

Codex Chapters use Scout Companies to train new recruits. If the League has no Scout Companie, does this mean each Company recruits and trains new Marines on its own? That the League consists of nine Companies with 111-112 Marines each?

 

This is a very good point, the increased numbers in the 2-9th companies could be a way forwards here, possibly mirroring the methods what the Black Templars use with their Neophytes (essentially, acting as squires to a Battle Brother, learning from that particular Astartes' craft in battle)?

 

But the Chapter does not use ground vehicles, almost at all.

This a stupid limitation. Flyers are NOT stealthy during atmospheric reentry, i.e., while transporting Marines from their starships to planetside battlefields; additionally, inclement weather and enemy air defense may prevent flyers from being used at all, as they do in real life.

Ground vehicles thus grant the League the ability to transport troops with relative speed (faster than walking, anyways) and stealth (stealthier than a flyer thundering and lighting up the sky during atmospheric reentry, anyways), as well as serving as platforms for Whirlwind missile launchers and other ordnance- the latter of which is CRITICAL to suppressing enemy fire so your Marines may live to storm enemy lines.

 

 

I would agree on this, the Chapter will need ground vehicle capability for a number of reasons, both tactically and out of necessity in certain combat environments where flying would be exceptionally hazardous or counter productive (notably a serious amount of enemy Anti-Aircraft weaponry or even environmental troubles).

 

Possibly push more to say the Chapter prefer the use of aerial assets for deployment and fire support, including Land Speeders etc, but they also maintain standard battle vehicles for use as needed, possibly favouring the newer grav-tanks?

 

They don't due attrition campaigns, bother holding ground, or engage in pitched battles.

So they have no way of enduring a siege? What do they do if the Red Corsairs attack the League's fortress-monastery in order to seize its gene-seed? If an Ork warband attacks an arms manufactory with the intention of using it to make all its members "Flash Gitz," will the League simply retreat and allow the foul xenos to drown the planet in shot, or destroy it to deny the xenos- pissing off the AdMech, and denying the Imperium arms the Emperor needs to defend His realm?

You have good ideas, but you need to think on the long-term consequences of implementing them.

 

On this one, a slight change of wording is in order to fix their desire to prefer rapid assaults etc to keep what you'd like and help it fit in better to how the Chapter would be forced to operate in a number of battle scenarios:

 

"The League of Heraklion prefer to fight in rapid shock assaults, heavily utilising their aerial assets for troop and fire support deployment to exact warfare in the method they are true masters at prosecuting, however the Chapter are more than capable of engaging in less kinetic battles when the need arises across their sector, including defending or breaking sieges, or dealing in more open-field battles."

 

As Bjorn has said, there's a lot of good ideas here, just needs a little tinkering to help it along to befit the effects of their battle methodology. :tu:

 

I'm looking forwards to seeing this one grow and develop. Remember, this is oyur Chapter to build on and to do as you see fit, we Liberites are just here to help it along with ideas, feedback and suggestions to possibly use or adjust.
 

Cambrius

[Bjorn Firewalker]

In a compromise, you could possibly go down the route of not having Heraklion being insubordinate to the Ultramarine Chapter Master, he was his commander after all prior to the events on Thrakion, so respect will be there. Instead, Heraklion and the new/surviving command staff petition the Chapter Master to allow the survivors of the Third Company to break away as their combat styles etc have become too divergent to ever truly fit back into the Ultramarines and the region they are in badly needs protection.

 

If this coincided with the Fourth Founding, it would be an apt possibility the Ultramarines then petition for the Sons of Heraklion to be regarded as a new Chapter, as the former Legion would certainly hold some clout in ensuring the High Lords of Terra permit it.

 

Good idea.

On this one, a slight change of wording is in order to fix their desire to prefer rapid assaults etc to keep what you'd like and help it fit in better to how the Chapter would be forced to operate in a number of battle scenarios:

 

"The League of Heraklion prefer to fight in rapid shock assaults, heavily utilising their aerial assets for troop and fire support deployment to exact warfare in the method they are true masters at prosecuting, however the Chapter are more than capable of engaging in less kinetic battles when the need arises across their sector, including defending or breaking sieges, or dealing in more open-field battles."

This is well-written.

[Volt]

 

 

A unique, NOT CODEX COMPLIANT organization is NOT characteristic of the Ultramarines and their descendants. Maybe claim the League is an Imperial Fists descendant instead?

 

Non codex compliant chapters are actually present amongst the known Ultramarine successors? Off the top of my head there's the Emperor's Spears, Iron Snakes, and Hawk Lords as fairly divergent, with the Ultramarines even having their fair share of mutants.

 

 

Codex Chapters use Scout Companies to train new recruits. If the League has no Scout Companie, does this mean each Company recruits and trains new Marines on its own? That the League consists of nine Companies with 111-112 Marines each?

1,000 line marines, organized into 10 Companies each with a 10+ man scout team attached for reconnaissance and kidnapping prior to invasion. Although I'm figuring the Chapter would mostly travel and deploy as a singular force and only breaking up to hit multiple targets in a single campaign, redundancy would ensure in their minds that any company always has the means to induct new members while off-world and scouts are never wholly wiped out in the loss of a company ship.

 

 

This a stupid limitation. Flyers are NOT stealthy during atmospheric reentry, i.e., while transporting Marines from their starships to planetside battlefields; additionally, inclement weather and enemy air defense may prevent flyers from being used at all, as they do in real life.

Ground vehicles thus grant the League the ability to transport troops with relative speed (faster than walking, anyways) and stealth (stealthier than a flyer thundering and lighting up the sky during atmospheric reentry, anyways), as well as serving as platforms for Whirlwind missile launchers and other ordnance- the latter of which is CRITICAL to suppressing enemy fire so your Marines may live to storm enemy lines.

Who said anything about stealth? The goal of skirmish tactics isn't to sneakily infiltrate troops before the enemy knows what's going on - you need aircraft to land ground vehicles in the first place, and it's not like a lumbering multi-ton vehicle painted in resplendent heraldry is any more stealthy than something as fast as a thunderhawk (depending on altitude) simply screaming in and blowing everything up. For example if the League of Heraklion were to attack a hive occupied by enemy heavy infantry - they would never enter the hive, there's no point. The slaughter would be brutal, they'd bleed personnel heavily, and the hive couldn't even be occupied by the marine force. In their minds it is far more efficient to completely cripple the hive by knocking out water filtration, food shipments, power generation, and fuel shipments. You leave the enemy to sit in the dark and die in isolation as they starve to death or they crawl out of their hole and get shot by the waiting guns. At most just a couple marines become casualties from errant meltagun fire, then they leave the mess for the Guard/Munitorum to clean up when they arrive.

 

As for Rhinos, they actually don't move faster than the running speed of marines (which can at least be kept up until the lactic acid buildup forces them to retire, such as the Crimson Fists who established the maximum of marine combat effectiveness without any rest), their main use is really ammo storage and ferrying wounded who aren't able to walk. Further, a whirlwind isn't any better or worse at suppressing the enemy than a couple sorties of Thunderhawks or Storm Eagles dumping turbolaser fire/rockets at the enemy. Or just calling in local orbital bombardment via macrocannon batteries to soften up the enemy.

 

 

So they have no way of enduring a siege? What do they do if the Red Corsairs attack the League's fortress-monastery in order to seize its gene-seed? If an Ork warband attacks an arms manufactory with the intention of using it to make all its members "Flash Gitz," will the League simply retreat and allow the foul xenos to drown the planet in shot, or destroy it to deny the xenos- pissing off the AdMech, and denying the Imperium arms the Emperor needs to defend His realm?

You have good ideas, but you need to think on the long-term consequences of implementing them.

 

In siege warfare, a fortress' role is not simply to be a fortification to defend from the enemy, but a delaying measure. The intention is that if the League finds out that say, Thrakion has been invaded by a Chaos Warband, they'd either draw the Warband away from the siege and hit them from orbit/overwhelming show of air superiority, or merely drop a macrocannon shell right on top of the siege camp so long as the void shield for their fortress was up. They don't fight fair, and their response to challenges of attrition is to do whatever the enemy would consider unthinkable, and catch them on the backfoot. The only exception, and true nemesis is the Tyranids - as a mindless swarm they are completely inured to skirmish warfare and could only be dealt with in the void. And even then the Chapter would at most be able to lead the tyranids on a wild goose chase series of void battles to merely buy time for the Imperial Navy to show up and actually solve the problem.