- Third War for Armageddon (999.M41) - The Omega Marines participated in the Third War for Armageddon, deploying the entire Chapter. Most notably, the Omega Marines deployed 9 Dreadnoughts, led by Brother Weylands, to support 8 Dreadnoughts of the Angels Porphyr Chapter in defence of the Ghattana Bay water processing plant's Gate IX. In the largest reported instance of cybernetic combat in Imperial history, this Astartes force was able to defeat an assault of equal size by Ork Killa Kans and Deff Dreads.
Notable Omega Marines
- Dreadnought Weylands - A Dreadnought of the Omega Marines Chapter, who led a contingent of 8 other Dreadnoughts to support 8 Dreadnoughts of the Angels Porphyr Chapter led by the Dreadnought Damos in defence of the Ghattana Bay water processing plant's Gate IX during the Third War for Armageddon. Together they defeated the Ork Mek force of Warboss Judrog Irontoof.
The Omega Marines wear a unique halved-heraldry with white on the right side and black on the left side of their Power Armour. The Aquila or Imperialis on the chest guard is dark yellow. The black squad specialty symbol -- (Tactical, Devastator, Assault or Veteran) -- is located on the right shoulder plate. A white Roman numeral is stenciled in the centre of the squad specialty symbol, indicating squad number. The colour of the shoulder plate trim indicates company number in accordance with the Codex Astates -- i.e. White (1st Company), Yellow (2nd Company), Red (3rd Company), Green (4th Company), etc. Veteran Marines wear black helms.
The Omega Marines' Chapter badge is a white Greek letter "Omega", with a large bone-white skull superimposed over it, centred on a field of black.
- Adeptus Astartes: Successor Chapters (Limited Release Booklet)
- Codex: Armageddon (3rd Edition)
- How to Paint Space Marines (Painting Guide), pg. 88
- Index Astartes: Dreadnoughts (6th Edition), pp. 5-7
- Insignium Astartes - The Uniforms & Regalia of the Space Marines, pg. 63
- White Dwarf 249 (UK), "Index Astartes: Emperor's Shield: Space Marine Chapters of the Armageddon War", pp. 30-33