Battle of Mordian
The Battle of Mordian was a battle waged on Mordian between the invading hordes of Chaos and the Mordian Iron Guard. The battle would prove to be one of the most significant events in history not just for Mordian but for the Imperium, as it represents one of humanity's rare victories against Chaos in preventing the loss of a world to damnation.
The seeds of Mordian's doom were sowed during an especially hot summer thanks to a secret conspiracy begun by greedy men seeking personal enrichment, even if it came at the expense of millions. This dark cabal met in secret in the depths of the planet and, making the necessary incantations to the Gods of Chaos, began weaving a spell. As countless innocent blood was spilled and many dark pledges were made to fuel the spell, the summer continued to grow hotter and strange tidings were reported in the capital: people disappearing without a trace, restlessness among the criminal gangs and cannibal mobs, and sightings of winged monsters. Finally the spell reached its culmination, and suddenly Mordian shook and the sky erupted in flames as ships from the Eye of Terror poured Chaos Space Marines from the skies and daemons appeared within the streets. In desperation the Tetrarchs, the ruling elite of Mordian, called upon their Astropaths to send a distress call, but the power of Chaos was such that their minds melted in the effort and it was unknown if their message got out.
Where lesser men turned and fled in the face of such nightmarish terrors and eldritch abominations, the Iron Guard stood firm. Among the most loyal and determined of the Imperial Guard, they laid low many a foe with volley after volley of disciplined fire and would have fought to the last man at that moment. Realizing their sacrifice would achieve nothing in the face of such overwhelming forces, the order to withdraw was finally given, and with reluctance the Iron Guard regrouped around Mordian's capital. While Chaos ran rampant across the rest of the planet, the Iron Guard fortified the capital for the final battle: every building became a fortress, every tower a strongpoint, and every street and plaza a killing-zone for the Iron Guard's carefully sighted weapons. The defence of the capital would be coordinated from the Tetrarchal palace itself, located in the center of the city.
When the final assault began the Iron Guard's preparations paid off, channeling the Chaos Marines into prepared fire traps where they were destroyed by well-disciplined fire. The defenders were caught off-guard however when a bedraggled horde of Cultists rose up from the sewers beneath them, sacrificing themselves in the thousands so that the Iron Guard was unprepared for the next wave of Chaos Marines and daemons. The forces of Chaos moved with purpose, but while they were forced to retreat the Iron Guard's lines never broke. As losses became too heavy or a position untenable they would withdraw to the next defensive line, preserving what they could of men and material. Street by street and building by building they fell back towards the center of the city with all the tactical brilliance and discipline the best Imperial troops could hope for, and yet eventually there would be no more ground to give.
Finally the Iron Guard were forced back to the Tetrarchal palace, their last stronghold on the planet, and in the glare of the burning city around them they fortified it for their final stand. Suddenly a daemonic horde of Nurgle was upon them, Great Unclean Ones shuffling forward beside rancid Plague Marines, preceded by a plague of flies which buzzed about the Iron Guard, crawling into their eyes and ears and filling their mouths with their hairy bodies. In response the Iron Guard spat volleys of death into the attackers with mechanical precision, never stopping or faltering in their routine as daemon gore ran like a foul river, but for every felled foe two more would take their place. At last Mordian Captains ordered their men to form a firing line on the palace steps, ready to give one last volley before the forces of Chaos fell upon them.
Unbeknownst to them the spell which had brought the foul creatures to Mordian had nearly spent all its energy, while beyond the planet's orbit Imperial psykers had been busy weaving their own counter-spell. At that moment the daemonic beings began dissolve before their very eyes and the sky changed back to its customary black, revealing the orbiting Imperial starships. Victory was achieved, thanks entirely to the Iron Guard and their heroic defence buying enough time for the psykers to work their abilities.