Siege of Hexodivus

The Siege of Hexodivus was an Imperial defensive campaign carried out by the Midnight Claws against the encroaching forces of an unnamed Ork WAAAGH! that threatened to overrun and conquer the Chapter's homeworld of Hexodivus. Due to the valiant and heroic efforts of the Chapter, they held their ground, halting the Greenskins' advance. But their victory came at a terrible loss as the all the Chapter's senior leadership - including their Chapter Master - were killed when their fortress-monastery was destroyed. Bereft of solid leadership, this would eventually have dire consequences for the Chapter, who would later suffer a terrible inter-Chapter war.

History
In the last year of M36, the Warboss and his WAAAGH! finally reached the Midnight Claws' chapter homeworld. Almost all of the Chapter's companies, with the exception of the 2nd and 9th Companies, were entrenched and ready to fight to the death for their homeworld. During the vicious battle that ensued, their fortress-monastery was destroyed leaving no trace that it ever existed. Everything within the Chapter's former citadel was lost, including a relic, Chapter Master Korbius and all the Captains, who were tragically killed. This left the Chapter bereft of solid leadership which would eventually erupt into an inter-Chapter schism that would last for hundreds of years. Some of the Marines left the Chapter for reasons unknown, only to be seen later as a Chaos Warband wholly dedicated to Chaos Undivided.