The Yellow Jackets is a Loyalist Second Founding Chapter of Space Marines of unknown origin. Emerging as a distinctive Chapter during the subsequent Great Scouring, this Chapter quickly became known for its lightning raids and hit-and-run attacks launched from Thunderhawk Gunships. For ten millennia, the Yellow Jackets have continued to steadfastly serve the Emperor of Mankind, both faithfully, and valiantly.
Following the end of the Horus Heresy, Roboute Guilliman, Primarch of the Ultramarines Legion and author of the newly-scribed Codex Astartes, was responsible for the restructuring of the Imperium's military forces. The vast Space Marine Legions would be broken down into numerous, smaller existing formations, known as a Chapter. When the Second Founding of the Space Marines was decreed seven years after the death of Horus and the end of his Heresy, most of the old Loyalist Legions divided into fewer than 5 Successor Chapters, but Guilliman's own Legion was divided many times.
The newly founded Space Marine Chapter known as the Yellow Jackets emerged as a distinct Chapter after the terror-filled era of the Heresy. During the Great Scouring, when the Imperium was venting its wrath by driving the remnants of the Traitor Legions of the wretched Warmaster towards the Eye of Terror, the Yellow Jackets were cut off from the bulk of Imperial forces. The Chapter began a campaign of hit-and-run attacks launched from Thunderhawk Gunships. The sudden appearance of these warriors pinned down and paralysed vast enemy forces and fear of their retribution prevented many a Planetary Governor from going over to the service of Chaos. In the ages since, the Yellow Jackets have continued to serve the Emperor of Mankind with distinction, including their heroic stand against Warlord Graznik and his mighty Ork WAAAGH!
The Yellow Jackets primarily wear black Power Armour. The Aquila or Imperialis on the chest plate, as well as the top of the helm, shoulder plate trim and lower legs are yellow. Two distinctive black rings are painted on the lower legs, emulating the distinctive markings of their insect namesake. The inset of the right shoulder plate is painted red. The yellow squad specialty markings -- Tactical, Devastator, Assault or Veteran -- are located on the right shoulder plate. Sergeants are designated by the skull symbol worn on their helms whilst Captains are designated by their red helms. A black Roman numeral is stenciled on the right knee guard, indicating squad number. The right knee guard is painted in the company colour in accordance with the dictates of the Codex Astartes -- i.e. White (1st Company), Yellow (2nd Company), Red (3rd Company), Green (4th Company), etc.
The Yellow Jackets' Chapter badge is a distinctive yellow wasp centred on a field of black.
- Adeptus Astartes: Successor Chapters (Limited Release Booklet)
- White Dwarf 177, "Golden Demon Space Marine Chapter Design Competition", pg. 30