Donatos War - The Hour of Betrayal: It was in this very moment that the Loyalists were struck head-on by the Chaos-tainted scrap-code. As some of the most complex creations of the Machine God, the suits of Knight Armour were partially shielded from the most extreme effects of the scrap-code. Where the Cherubim of the Heavenly Host had suffered catastrophic system failures, the Imperial Knights' Machine Spirits were strong enough to limit the machine-curse's baleful effects to none essential systems such as Auspex-arrays, communication systems and pictscreens. Others were not so lucky. On several occasions the scrap-code penetrated deep inside the systems of the Sacristan Crawlers, pushing their reactors into overdrive and causing them to explode. Overhead, several Thunderbolts tumbled from the sky, their engines unexpectedly cutting out while on the ground the targeting systems of Leman Russ tanks failed. While the scrap-code did not directly harm the Loyalist Knights, it left them disorganised, confused and in some cases blinded, a confusion the Traitors in their midst knew how to exploit.Unaffected by the Chaos scrap-code, the Traitor Knights of House Chimaeros opened fire at point-blank range on their former allies, while the Knights of House Wyvorn assaulted House Pegasson. One of High King Tolwyn's bodyguards, Sire Daeved was the first Knight to realise the betrayal. Just before his exterior pic-feed cut out, Sire Daeved saw a Chimaeros Knight preparing to fire upon the High King. Unable to warn his liege or reorient his Ion Shield in time, the king's bodyguard used the bulk of his own Knight to intercept the incoming fire, his steed losing an arm in the process.A little bit further along the battleline, Danial Tan Draconis, the Kingsward, was also attacked. Still reeling from the unexpected blow, House Draconis had little time to react before House Chimaeros charged into their midst. Sire Rosierre Dar Chimaeros, one of Viscount Gerraint's most seasoned warriors, attacked Danial. Hastily parrying the first blow with its Reaper Chainsword, Danial's Knight Errant, Oath of Flame, was pressed back, the battlefield already littered with fallen Knights belonging to House Draconis. Through a mix of luck and skill, Danial Tan Draconis was able to slay his opponent while his father frantically tried to come to grasp with this new situation.All across Donatos Primus and even in orbit, the forces of House Chimaeros and House Wyvorn revealed their true colours. On the surface, House Chimaeros' assets had split into two groups. The first had charged at House Draconis, seeking to slay its ruling Nobles while the second assaulted House Minotos with devastating enfilade fire. Within the first solar minutes of the betrayal, fully half of Grandmarshal Gustev's Exalted Court had been slain.Behind the main advance, the Sacristan Crawlers belonging to the Renegade Houses battled their Loyalist counterparts, while on top of the hab-mountains the enemy revealed an unexpected weapon: Macrocannons large enough to repel voidships. The colossal weapons opened up on the forces of House Pegasson and exacted a heavy toll. In orbit, House Chimaeros and House Wyvorn bastion-ships unleashed the firepower of their batteries against the Imperial ships. Dormant Plasma Torpedoes were reactivated, wreaking havoc on the Imperial flotilla. Even more disturbing was the fact that these torpedoes were seemingly of Astartes design: the Word Bearers had finally decided to get involved in the fight.With the scrap-code still paralysing all communications save for short-range Vox-transmissions, House Draconis needed an alternate means of communication. The solution was found by Tolwyn's daughter, Gatekeeper Jennika Tan Draconis, who was the first to order her lance to communicate through the ancient Squire's Code. Her Knights raised their auto-pennants in precise order and formation to convey messages to those within their line of sight. Although limited in words, the Squire's Code gave House Draconis the means it needed to reorganise their formation. Luckily, High Sacristan Polluxis had succeeded in warding his Land Crawler and its tactical Auspex from the data-infestation. His Auspex readings showed him what the High King had ignored so far: that the Tanhollis and Mubraxis regiments had been pressed back by the enemy, now led by Varakh'Lorr's warband of Heretic Astartes drawn from the Word Bearers Legion, the Scribed Blade.With the enemy's best warriors pressing in on both flanks and his supporting troops overrun, the High King recognised that the battle was lost. Of the supporting Astra Militarum regiments, only the Cadians were still in the fight, gathering protectively around Polluxis' Sacristan Crawlers or standing against the turncoat Chimaeros Knights. Finally, using all his technical knowledge, High Sacristan Polluxis managed to reach the forces of House Pegasson and House Minotos and delivered the High King's order: retreat. Gathering around Tolwyn's Knight, Fyreheart, the surviving 57 Knights of the three Loyalist Houses fought their way through the encircling troops.