|Battle Cry||Skovakarah uhl zarûn! (Redden the Earth!)|
|Chapter Master||High King Arucatas the Swordbearer|
|Specialty||Air-to-ground assaults, Drop Pod assaults|
|Colours||Light blue with white helmet and aquila; Druids (Librarians, Apothecaries, Techmarines, and Chaplains) wear black armor with white helmets instead|
"Cousin. Do you use actual lions, celestial or otherwise?"
"Then shut up about us using spears."
- – Aaron Dembski-Bowden's take on the Emperor's Spears
The Emperor's Spears are one of those many, many chapters who nobody has ever heard of, or at least until Aaron Dembski-Bowden wrote a book about them, set after the Gathering Storm. They were one of the three Chapters stationed to watch over the Elara's Veil region, the others being the Star Scorpions and the Celestial Lions. Unfortunately for them, the Star Scorpions were lost in the Warp and the Celestial Lions are still rebuilding after their spat with the Inquisition so they're more or less stuck watching the sector on their own. They are mostly Codex-compliant, but have dispensed with using the standard companies in favor of using autonomous warhosts, the better to cover the region.
Nemeton is a pre-industrial world dominated by vast oceans, and the Emperor's Spears' share the native tribes' superstitions about rain being a sacred gift from the sky, which annoys the Ecclesiarchy to no end. The Astartes interact little with them, and in turn the natives believe the Emperor's Spears' to be the spirits of lost children who take their young away never to be seen again.
Following a dispute with the Aurora Chapter over matters of honor that boiled over into a full scale conflict, they have become estranged from their primogenitor (who settled the dispute in the Aurora Chapter's favor; the Spears insist that they did so as an act of favoritism). The tensions have eased somewhat since then, but the Spears and the Aurora Chapter still refuse to fight together.
ADB has given some details about their look and culture through some forums. They mark ranks with helmet plumes of various colors and are basically Spartans in SSPPPAAAACE compared to Ultramarines being space-romans. Alternatively, the Emperor’s Spears may have a distinctly Ancient Briton theme, from their use of Ogham Runes, Woad Blue colouring, organisation into semi-autonomous ‘Warhosts’ and their use of distinctly Brythonic flavoured titles such as ‘High King’ and ‘Druid’. Their allied forge world, Bellona, is also the name of a Romano-British goddess. They also semi-worship the rain - just like the British.