The Desert Lions are a Loyalist Codex Astartes-compliant Space Marine Chapter. They are a Second Founding Successor Chapter of the Ultramarines Legion. They are known to have fought during the military campaign known as Operation Carthage during the Great Scouring in 31st Millennium, following the defeat of Warmaster Horus and the Traitor Legions, to retake the world of Istvaan V from the Forces of Chaos who had controlled it since the first days of the Horus Heresy. Little else is known about the Chapter in current Imperial records.