M'gala Excoriation

The M'gala Excoriation was an Imperial excoriation campaign conducted by the Shattered Star Space Marine Chapter against invading Heretic Astartes of an unnamed Chaos Warband upon the Imperial world of M'gala.

History
When the planet of M'gala fell under siege by a chaos warband, the chapter made it's way to the system. When they arrived, they found their missing brothers that had disappeared in the warp nearly a millennia earlier. Their lost brothers claimed that the planet was revolting as the two fleets met each other and launched an orbital drop pod assault into the capital city. When the battle was at its fiercest, the lost brothers revealed their true allegiance and immediately launched a deady bombardment on the city, killing many loyalists and traitors alike.

Why the traitors killed their own is up for debate, but the the most likely answer is to weed out those who may betrayed the current Lord of their warband. A brutal battle ensued between the former brothers. After the battle ended the traitor Astartes fled into the Eye of Terror and would not to reemerge for millennia. only a select few people outside the chapter know of the true origins of the traitorous Shattered Stars, who now called themselves the Wraith Claws Chaos Warband.