Battle of Keylek
The Battle of Keylek was a battle fought by the Luna Wolves during the Great Crusade. Approximately 123 years into the Great Crusade, the Luna Wolves discovered the world of Keylek and the species that called it home, the keylekid.
Horus expected a prolonged struggle against such formidable foes, but the keylekid responded to the battle by first contact by assembling in large pre-exisitng staging grounds all over their domain and awaited the arrival of the Luna Wolves. The keylekid philosophy regarding warfare required them to fight only in these spaces, open-walled roofed structures several kilometres in area.
Maloghurst suggested that the rules of engagement remain in their favour. Rather than meet the keylekid in open combat as they expected, the Luna Wolves destroyed them from afar. The Wolves took to naming the keylekid battle halls "slaughterhouses."