Rules of Engagement (Anthology Short Story)

Rules of Engagement is an anthology short story published in The Horus Heresy series that was originally part of an anthology novel. Rules of Engagement was first published as part of the Age of Darkness main series anthology in May 2011. The cover image used is that of the e-book version Rules of Engagement which was released alongside the original anthology.

Synopsis
Roboute Guilliman has put the finishing touches to his great work - the Codex Astartes. This tome will show his Ultramarines how to deal with any tactical situation, no matter the foe. But as the Horus Heresy reaches Ultramar, Captain Ventanus of the Troublesome Fourth must test the strictures of the Codex Astartes against the one foe that the Primarch never expected: other Space Marines.