Ollanius Piers was an Imperial Army trooper of the Hundred and Fifth Tercio Upland Grenadiers Regiment during the Siege of Terra. During the battle for the Eternity Wall Spaceport, he was interviewed by Historian Hari Harr.
Piers recounted his battle for the Pons Solar bridge, where he stood before a World Eater until Jenetia Krole arrived to dispatch the traitor. Thinking the story lacked enough significance, Harr changed the World Eater to Warmaster Horus himself.
Later, as the Eternity Wall Spaceport fell, Piers stood his ground against Angron and was slain.