Titanicus by Dan Abnett

In a galaxy torn by war, the Forge World of Orestes becomes the stage for a colossal conflict as the Imperium's mighty Titan Legions face off against a relentless Chaos invasion. As towering war machines clash, the fate of the planet hangs in the balance, with the defenders struggling to maintain their grip against overwhelming odds. Amidst the chaos, personal stories of courage, sacrifice, and betrayal unfold, revealing the human cost of war and the indomitable spirit of those who fight to protect their world from annihilation.