The Adeptus Custodes never exceed ten thousand warriors at any given time.
Guided by psychic divination and the intelligence gathered by shadowy agents, they strike down demagogues and warlords who might otherwise raise invasion forces against the heart of the Imperium. While they were created to defend the Throne World, the Adeptus Custodes have recognised that the most effective way to safeguard Terra is to take a proactive hand in the ongoing battle against Mankind’s innumerable foes. 10,000 years ago the Custodians were created by the Emperor as his companions and sworn bodyguards.