Force Commander Idrion stood at the edge of the ridgeline that overlooked the small pass, one of two leading to the entrance to his base. At his side were a pair of heavy bolter turrets, and two squads of Marines with Heavy Bolters and Missile Launchers, as well as a small squad of Scouts armed entirely with sniper rifles. His bodyguard of Terminators stood loosely arrayed in a semi-circle, and behind them, the Chaplain stood haughtily surrounded by the close combat Terminators.
Garbled reports, requests for back up, and screams were coming over the comms still. The 923rd regiment had been annihilated an hour ago, and the 223rd and 737th were under heavy assault at this time. Idrion's base had so far only received light probing attacks. The screams slowly became less and less in number until only one voice could be heard. Idrion recognized the voice of Colonel Tyrion, "Astartes. If you can hear this, the battle is lost. Flee this world, we cannot defeat this foe. Not even your might can stand against them. Flee before the Tyranids."
Idrion strode to the forefront of his base, where six heavy bolter turrets, four squads of Marines with an array of special weapons, two squads of scouts, and a Dreadnought, Brother Palmyris, stood silent and solemn watch. In the distant darkness, skittering things moved from cover to cover in a vast tide. Idrion grimaced darkly when he heard the heavy bolters upon the hill open up. He returned to the teleportarium deep inside the base, and waited.
The first strongpoint fought valiantly, the turrets reaping a toll of blood and ichor. The marines fell back as the Tyranid bioforms moved to engage them in close combat, back to a second line of turrets around the bend in the pass. Mines covered the area between the two, and two squads of scouts with snipers were perched on several ledges above this bend. A whirlwind, several more dreadnoughts, and a predator all lurked around this bend as well, in addition to four more squads of Marines. Two additional squads of Assault Marines sat ready upon the edge of the ridge.
The Tyranids kept coming despite the horrific losses wrought upon them. They swamped the mines with too many bodies to count, and discovered the scouts by bombarding the entire Cliffside with their vicious seed-pod weapons. They ran into the steel line of turrets and tanks and Marines. In the first instant of battle joined, ten thousand Tyranids died. And a hundred thousand more swept up to replace them. A trio of massive Hive Tyrants led the enemy forces, and Idrion gave the order. The Assault Marines dropped from their perch like armored missiles while the two squads of terminators teleported into the midst of the Tyranids. The tanks and dreadnoughts surged forwards, smashing into the front ranks, and the Tyranids were smashed and scattered, but not broken. A furious swirling melee erupted. Idrion stood face to face with the largest of the Tyrants, and he knelt to the ground, tapping his comm-bead, "All vessels in orbit, fire upon my signal."
A scything talon ripped him in half, and the resurgent tide swarmed over his dying men, blood spattering and metal being shredded. And then, a glorious golden light suffused several areas of the battle, as if angels were descending from on high. It intensified as the targeting laser confirmed sensorium reports, and massive lance blasts fired, scorching great swathes of Tyranids from existence...
Dawn of War: Dark Crusade: Tyranid Mod
Basically, I died in my little corner fighting them, and the last thing my Force Commander does is his orbital bombardment, and this is what I pictured.