Sentinel: Chaos boxed in

As 03.012M42 came to an end, the Eldar on Sentinel changed their axis of attack, swinging out east from their positions near the Sentinel Prime Compound and assaulting the forces of Chaos in their last bastion at the Scrap Recycling Facility, some 200km away.

The Eldar found more than they bargained for however, as the expected weakened forces of the Iron Warriors and Enraptured had been replaced in complete surprise by the elite forces of the Moonface Catechism. The Catechism had moved in in secret, using their arcane device to ship their new found allies to the Rim Worlds.

Imperial intelligence postulated that the Catechism was in fact intent on removing as many forces as possible from the planet, to re-inforce the Chaos worlds in the Zadoc subsector prior to the expected invasion by Nemesis. Even so, the Catechism deployed their own forces into the Sentinel theatre, and a bloody battle erupted between the forces of Chaos and the Eldar.

After several hours of brutal fighting, the result was a stalemate. However, the Catechism had taken a battering from the arcane weaponry of the ancient aliens, and were forced to fall back. Unfortunately, they didn’t have anywhere to fall back to.

Instead of retreating off world through the Device portal, the remaining traitor legionaries instead launched a violent assault on the Sentinel spaceport, taking the Ultramarines who had recently arrived via strike cruiser completely by surprise. The Ultramarines chapter had agreed to replace the battered remnants of the Red Angels in the defence of the Imperial world, but no sooner had they arrived than they found themselves in battle against an old foe.

The ferocity of the attack caught the Ultramarines on the back foot, the knowledge that there was nowhere to retreat spurring on the half-crazed Chaos marines. After several hours of bitter fighting the Catechism took several of the eastern installations of the vast spaceport, forcing the Ultramarines and Imperial guard regiments into an ever tightening perimeter around the landing strip. With the Eldar on one side and the forces of Chaos on the other, General Ritchie began to consider abandoning the spaceport by airlift, but knowing the strategic value of the installation, he elected to follow the Astartes plan to dig in with his remaining forces and launch a rescue mission from the Alenia hills as soon as was possible.