Book 1 in the Space Marines Battles series by up-and-coming author Steve Parker.

When the ork hordes of Warlord Snagrod lay waste to the planet of Badlanding and wipe out the Crimson Fists sent to stop them, Chapter Master Kantor prepare a hasty line of defence on the Fists homr planet of Rynn's World. Tragedy strikes when an errant missile destroys the Space Marine's Chapter monastery, killing most of their warriors. With a handful of Crimson Fists left, Kantor must fight the campaign of his life, to defeat Snagrod's orks and prevent his Chapter's annihilation.