In late November, eighty-thousand Babylonians marched into the outskirts of the city. 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. Whilst the Babylonians ran rampant across the rest of the city, 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 enemy troops into prepared fire traps where they were destroyed by well-disciplined fire. The defenders were caught off-guard however when a sea of infantry rose up from the sewers beneath them, sacrificing themselves in the thousands so that the Iron Guard was unprepared for the next wave of Varangian Guard and Heavy Armour. The Babylonians moved with purpose, though whilst 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, and in the glare of the burning city around them they fortified it for their final stand. Babylonian shells rained down upon them, and in response the Iron Guard spat volleys of death into the attackers with mechanical precision, never stopping or faltering in their routine as Babylonian blood ran like a foul river, but for every felled foe two more would take their place. At last the company Captains ordered their men to form a firing line on the palace steps, ready to give one last volley before the forces of the enemy fell upon them. In his last breath, Captain Dennos of the 33rd regiment of line called in an artillery barrage on their position, annihilating themselves and their attackers.
The city was destroyed and its defenders slaughtered, but the Iron Guard had completed their objective- the Tetrarchal palace had not fallen to the enemy, for there was no palace left to claim.