Defence of Gemstone-IV

The Defence of Gemstone-IV was an Imperial castigation campaign conducted by multiple detachments of the Zero Legion Space Marine Chapter against an unnamed Orks WAAAGH! that invaded the Imperial hive world of Gemstone-IV,

History
The Zero Legion Chapter's 6th and 19th Divisions appear to aid the besieged Hive World, Gemstone-IV from a massive Ork WAAAGH! The 7-week campaign is the first time the Zero Legion works alongside Imperial forces. The 19th Division assists in reorganizing the Planetary Defense Forces, while the 6th Division attacks the Orks' lines from the rear as well as eliminate several Ork Nobs. The Ork Warboss is later killed while trying to attack Imperial lines, slaughtered along with his forces by the 19th Division's defensive lines, while the 6th Division kills any possible Ork uprisings, as well as collect samples of Ork DNA, in order to learn how the species reproduces and find a way to suppress it.