Codex: Chaos Space Marines (2007), p32 — Daemon Prince

The most infamous Daemon Princes come from amongst those Primarchs who sided with Chaos during the Horus Heresy. These are those Primarchs who turned on the Emperor and led their Legions into damnation. Yet for all of the Imperium's hatred levelled at them by the Inquisition, the Daemon Primarchs Angron, Magnus, Mortarion and Fulgrim are content to wage wars against their enemies within the Eye of Terror. It is almost unheard of for them to lead forth their warriors from their Daemon worlds, preferring to leave such petty tasks to favour-seeking, fanatical underlings.