Year of War 40k: Apocalypse Part 1

Watch-Master Pyrannius examined the auspex display and sighed. Mere hundreds of feet away were the powerful walls of Valdegard, once the military and administrative center of the planet's local government. As the ancestral home of the planet's Warlord (a positon roughly equivalent to an Imperial Governor), the walls were impressive. Solid worked rockcrete walls hid a complex skeleton of plasteel reinforcements and specialized void shield arrays made the stronghold a nightmare to assault- though, unfortunately, the filthy traitors who now occupied the walls never even had to fire a shot before the city fell.

Apparently the corruption started at the top on this world, and the current Warlord invited the blasphemed legions of Chaos into his very home. It is said they looked to be loyalist Dark Angels- and by the time the local defense forces realized their deception other heretics had overwhelmed their positions. Now the blood-stained banners of the traitors flew high and proud above the walls he would now have to overcome.

You see, near Valdegard's center there had been strange reports. A hidden chamber beneath the town square suddenly revealed by construction, filled with strange bone-like structures. A huge statue of ivory crackling with alien power. Pyrannius had to either remove it or destroy it- which was a task made far more difficult by an enemy power occupying his objective. Luckily he didn't have to attack the fortress alone, and even now two regiments of the Guard (most notably the Vostroyan Infantry and an Armored Spearhead led by a powerful Shadowsword) were starting their assault. Turning, the Watch Master pulled his glaive from the wall and gave the order to begin the descent. The attack was about to begin!

Strikeforce Obsidian, backed up by the 'Litany of Annihilation' Shadowsword
tank.

Most of the reserves- all in tanks or able to arrive via deepstrike. 

The Fortress of Valdegard and the ruins of the surrounding suburbs.

The Litany and Corvus (as well as some guard) attempting to take on the fortresses
left flank.

A Kill Team makes its way through a graveyard while Vostroyen Heavy
Weapons Team fill the ruins.

A closer look at the vindicare, with Brother Balthasar the Ven. Dreadnought
supporting two blobs of conscripts.

The Vostroyen Leman Russ and the Deathwatch Razorback 'Oathmark' set up
the heavy hitters on the far right flank.

Chaos warbands dominate the long right side of the wall, supported by an
Infernal Defiler. 

Chaos sigils lift high, even as the traitor Dark Angels (Fallen? Alpha Legion?)
take up positions in the towers. 

Unbeknownst to the defenders, Aleksandr the Culexes Assassin is already in position.

First blood! Casimir the Vindicare Assassin kills a Dark Angel
Primaris Lieutenant directing the Devastators. 

Without fear or heisitation the Corvus (filled with a Kill Team and Watch Master Pyrannius)
flies over the walls, killing a Scout with its bombs before lighting up the defenders. 

After a relatively poor turn of shooting at the walls, the Fallen responds to the Shadowsword
threat with a deep strike assault to mixed success.

The Deathwing Terminators (if they can really take that title) also jump
in, looking to counter the troops inside the Corvus.

Deadly accurate Krak missiles from the Chaos Warbands take the
Oathmark out of action.

Oh no! A twist, Ork Roks rain from the sky, unloading whole mobs
to bring their own version of war to the world- though it will be the
Imperials who take the brunt of their assault. 

A War Wagon, and whole mob of Power Nobs. 

On the far right we see Killa-Kans and other armored targets smash into the
Vostroyens. 

And the last Rok lands hilariously directly 'onto' one of the walls, crushing
all the defenders...

... And unleashing a horde of bikes!

The wall is breached for the second time, with Deathwatch fighting a
successful (if bloody) campaign on the left flank! 

The last traitor Dark Angel in the tower died with a snarl that turned to a gurgle as Pyrannius's glaive sliced through armor and bone. How the forces of chaos had a Primaris Marine in their employ, he did not know- or even if the figures swollen corpse was the work of the Imperium or some foul Chaos sorcery. Even now his men were taking to the walls, but below?

Over every channel of communication, Imperial Guard were screaming. Hyper accurate fire from the walls decimated waves of men even as the greenskin hordes ran rampant through their lines. Foul Orks- how they came to this world through the Imperial Fleet overhead was a mystery to him, but he could not focus upon their paticular brand of foulness now. He watched as Brother Sergeant Arden, a marine wearing the brilliant white wings of a loyalist Dark Angel, pick up the false Chapter Banner and toss it over the wall. If he had anything to say about the foes which surrounded them, he was keeping it to himself.

"-- atch Master, come in!"

"Speak."

"Kill Teams have dropped into the Fortress. They are fighting their way to objective now."

"Understood. We will continue fighting here. Strike swiftly brothers."

Now, all they had to do was hope that the reinforcements rolling up would be enough to hold the attention of the Chaos forces. They would soon see...