The Cacophony

The Cacophony was a lamentable event that occurred in the history of the Ordinators Space Marine Chapter when their Chapter fleet was set upon by the infamous and hedonistic Knights of Laeran Chaos Warband. These zealous worshippers of the Pleasure God Slaanesh launched a surprise assault upon the Ordinators fleet and severely damaged several of the Chapter's vessels. In the end, victory was achieved at an extremely high price, but fortunately, the intervention of the Primarch Roboute Guilliman, ensured that the Chapter's survival by introducing the surgical techniques to transform their Astartes into Rubicon Primaris Space Marines.

History
A brutal ambush by a massive Knights of Laeran fleet against the 2nd, 3rd, 4th, 5th and 8th Companies of the Ordinators aboard the Battle Barge Paladin and Strike Cruisers Herald of the Sacred Wrath and Purifier as well as two escort Gladius-class Frigates - Victory of Light and To Justice Due - lead to the deaths of nearly a third of the entire chapter. All but one of the ships were either grievously crippled and effectively destroyed or outright exploded from massive plasma reactor detonations under a withering hail of lance fire and aggressive Slaaneshi Terminator boarding sabotage teams at the cost of very few destroyed Laeran ships. Only Centurio Ulixes aboard the Purifier manages to escape after Centurio Brutus, the Master of the Fleet, orders an emergency disengagement.

Less than one year later, the Stolos Omega Fleet of Forge World Ferunus arrives and fights off the still-looting Knights of Laeran and rescued the ship hulks with colossal recovery ships - along with hundreds of Brother-Initiate bodies. Miraculously, Centurio Brutus (and around 40 other Ordinators) survived the near-destruction of Paladin through the use of his Mucranoid Gland and swears vengeance by taking the chapter's Sacred Oath of Justice, alongside Centurio Ulixes and Legatus Aurelian, against the massive Slaaneshi warband. Massive cultural changes are forced to occur within the Ordinators, and, if only for the blessing of Guilliman, the creation of Primaris Marines from the chapter's Scouts begins using the surgical technique pioneered by Belisarius Cawl. Preparations for a massive war begin shortly after.