9th Black Crusade

The 9th Black Crusade was a Black Crusade led by the infamous Chaos Champion Abaddon the Despoiler and his Black Legion, launched out of the Eye of Terror in 537.M38. During this time, the Lamenters Space Marine Chapter was recalled along with a number of other crusading Chapters by the High Lords of Terra in M38 to help deal with the rising threat of incursions from the Eye of Terror. But the Lamenters' fell reputation for suffering bitter reversals and dark turns of fate, worked against them during the Chaos attack on the Hive World of Corillia during the 9th Black Crusade. The superstition-bound Mortifactors Chapter refused to fight alongside the Lamenters, abandoning the planet rather than serve beside them. Unwilling to desert the hive world's population, the Lamenters held out alone against the Black Legion onslaught for six standard weeks, suffering horrendous losses until the Ultramarines and White Scars led a battle group that broke though the Chaos fleet to relieve Corillia. Reduced to barely 200 surviving battle-brothers by their sacrifice, the Lamenters were deemed lost when their fleet disappeared in a Warp storm soon afterwards, only to reappear more than a century later on the edge of the Segmentum Solar having slowly battled their way back from the outer void.