Master Tracto's armored gauntlet smashed into the console, sparks flew as wisps of smoke crept through the newly formed cracks. It was the only outward sign of frustration he would allow himself. His head was low and his eyes closed as if in prayer. Those about him on the bridge stood solemnly at his side, the losses that day had been heavy. A Thunderhawk Gunship was on its way back to the Dark Angels command barge in orbit. The remains of Tracto's handpicked interdiction force aboard, some alive, as well the manyvdead of those bodies that could be retrieved.
The motionless body of Librarian By-Tor also lay in a stasis chamber, his armor torn asunder, and a pulsing mass of thickly scaled tentacles seemed to have erupted from the hole in his chest. His future was uncertain. He had been laid low before the marines ever began their combat action. A Hive Tyrant's Venom Cannon arced over a screening squad of tactical marines and shredded the Librarian's ancient power armor as if it were a Guardman's flak vest, flinging him to the ground before he ever sighted in the enemy.
Tracto watched the grainy, monochrome image of Scout Captain Winter on the holosphere. Winter's snipers fired round after round into a swarming mass of advancing Genestealers, but to no avail. It was sickening to watch as the clawed horrors bounded up the building's side and engaged the scouts in bloody melee. The last image was of a lone Winter, fighting impossible odds, combat knife in one hand, a Genestealer's throat in the other, being dragged down under the weight of half a dozen chitinous murderers.
Across the field of battle, another group of scouts charged from wooded cover, shotguns blasting, into a swarm of Termagants...only to fall moments later. A jump-pack equipped assault squad engaged the swarm's Hive Tyrant to avenge the fall of By-Tor, but to no avail. This wasn't a simple loss, it was slaughter. A lone tactical squad emerged somewhat victorious, their rapid fire boltguns destroying a swarm of Termagants as well as a swarm of what looked like nothing more than, well, swarms. The remainder of these tactical also expertly engaged the Hive Tyrant, tying it up for the rest of the battle.
The Dark Angels don't fling themselves carelessly into battle, every military action is carefully planned. Although the interdiction force sent out to engage the Tyranids was outnumbered, it was determined that the strength of the Dark Angels was evenly matched to the foes arrayed against them. Oddly enough, the battle did not play out as evenly matched as planned. The Tyranid swarms appeared to teem with even greater numbers than originally thought.
The saving grace of the battle was Assault Squad Icarus, who had been waiting in reserves. They were able to deep strike behind enemy lines and lay waste to the flanks and rear of many Tyranid elements. Flamethrower, bolt pistol, and chainsword were all used to extract vengeance in the name of the Emperor. Icarus' veteran sergeant Obduro saw his men eventually get cut down, but he carried on. Singlehandedly he cut down the Biovore monstrosities that had been lobbing spore mines the entire engagement. He also slew the remaining Genestealers. He carved out a victory on the field of battle using sheer willpower.
Here's the complete battle report.