Editing Ryza (section)

==Horus Heresy==

During the Heresy, Ryza became the target of those elements in the Dark Mechanicum who had resented its meteoric rise to power and now sought to tear it down for the glory of the Warmaster. Fortunately for the Ryzans, they had predicted ''some'' kind of civil conflict was coming and had spent decades preparing themselves for it, hence why they had been so aggressive in expanding the Warmongers' reach and power. Several of the Legio's battle groups were destroyed in major engagements such as the Battle of Molech, but they had grown so powerful by this point that they were able to shrug off what would have been crippling losses to any other Titan Legion. Such was not the case when the traitor forces rolled up to Ryza itself. Horus sent a large Dark Mechanicum force to invade Ryza as he was preparing to march on [[Terra]] itself. This force was made up of elements from multiple Forge Worlds that had pledged themselves to Horus and wanted to [[Ork|loot the shit out of Ryza and/or trash it beyond recognition]]. Two full Titan Legions were sent with this force, ''Legio Vulturum'' (the Gore Crows) and ''Legio Magna'' (the Flaming Skulls), along with a detachment from the infamous ''Legio Mortis'', the Death's Heads. In response, Ryza mustered the Warmongers, plus ''Legio Osedax'' (the Cockatrices) and ''Legio Honourum'' (the Death Bolts), along with backup from several Knight Houses, including Taranis, Zavora, and Ioeden. Even with such a powerful force, the Dark Mechanicum found the going heavy. They were able to take the gateway station on the moon of Ryza Secundus, but despite this their initial attacks on Ryza itself were thrown back with ease. A fifth column of dissidents and traitors rose up and managed to force the loyalists to spread their forces more thinly across the planet, allowing the Dark Mechanicum to set up a trap at the spaceport of Conveyance Terminus Nine-Omega that destroyed the Death Bolts and threw the loyalists onto the defensive. A series of Titan-vs-Titan battles ensued, with the Cockatrices and Warmongers suffering heavy losses. A group of Warmongers led by the Legio's senior princeps made a last stand at the Salvation Isthmus, a key chokepoint between Ryza's continents, allowing the loyalists time to regroup at the planetary capital of Prosperity. Unfortunately, Prosperity fell shortly thereafter to internal sabotage, forcing the loyalists to retreat to the forge city of Endeavour. After a series of seesaw battles, the loyalists recaptured Endeavour, broke the Death's Heads, and slew their commanding princeps. Ryza's ruling hierophant cracked open the planet's war vaults, unleashing their previously forbidden technology on the traitors, and a brand new Knight House, Sidus, emerged from beneath Endeavour, having been kept hidden for this very moment. As the traitors retreated to Nine-Omega, they enacted a scorched-earth policy, demolishing everything in their path and leaving Ryza a broken and sundered world. Most of the traitor forces managed to escape, while those that were left behind were obliterated by the vengeful loyalists. The Imperial forces had won, but it was a pyrrhic victory. Four-fifths of the planet's industrial capacity was wrecked in the battle, and the loyalist Titan Legions and Knight houses had been decimated.