The Greenskins were present on the moon Grimmig during the Adrilles War, but are missing from not only most of the Imperium reports filed during the war but also the writings of historians on the topic of the war. This is surprising because Orks are known as a savage, war-mongering race and, therefore, if a war was being raged in a system where they were present one would think they would take up arms simply for the pleasure of killing.
A reasonable answer comes by way of the Adeptus Mechanicus. On the topic of the Assault on Grimmig, the Adeptus claim the Orks fought alongside Sautekh Necrons in defense of one of the refineries the Tau and Jager Corps had hoped to secure and detonate. Most would dismiss this alliance as highly unlikely but there is one personal journal entry from a Jager Corps Marine who survived the Assault on Grimmig that lends credit to the Adeptus Mechanicus’ claim.
“We took up position beneath the catwalks of the refinery. Pipes along the ground were cracked and seeping and the air was thick with the smell of fermentation. From where we stood I could see Greenskins trudling along a catwalk some fifty yards from our position. Their movement was disorganized, sloppy, with staggering Orks stumbling into one another, and shots fired at random with no viable targets in sight.”
The Jagers’ journal entry places the Orks at one of the battles of the Assault on Grimmig, but it also suggests some of the Orks were drunk and disorderly.
The Adeptus Mechanicus have nothing to say on the sobriety of the Orks, but they do write that the Orks stayed at the refinery after the battle had ended. The Greenskins scavenged the battlefield and used the spoils to not build engines of war but to repair the refinery.
Notable battles of the Adrilles War in which the Orks participated:
The Orks remained in and around one of the refineries on the moon Grimmig.
Skabog was the Warboss of the Orks residing on the refinery on Grimmig. It was Skabog who entreated with the Sautekh Necrons in the days leading up to the series of battles known as the Assault on Grimmig.