Timeline of the Warhammer 40,000 Universe - Devastation of Baal (ca. 999.M41 - Unknown Date.M42): After sacrificing the Shieldworlds of the Cryptus System to fend off the xenos' earliest advance on the Baal System, the planet of Baal itself came under intense attack by Hive Fleet Leviathan. The Tyranid hive fleet was of such mass, even after its considerable losses, that it blotted the stars from the skies. Lord Commander Dante bolstered the formidable defences of the Blood Angels' Chapter homeworld and its moons like never before. Not one to await attack, Dante also sent forth scores of preemptive strike forces to delay, mislead, and whittle down the living armada. Hundreds of splinter fleets were thus defeated. Dante's call, beseeching the Blood Angels' successors among the Sanguinary Brotherhood to send immediate aid to their parent Chapter, did not go unheeded. The Flesh Tearers were the first to arrive, and ultimately all the Successor Chapters save the Lamenters answered the call. Even the Knights of Blood, who had been declared Excommunicate Traitoris by the High Lords of Terra, arrived to bolster the defences.It was still not enough. Learning at an exponential rate, Hive Fleet Leviathan could not be thwarted by the same strategy twice. Advancing steadily, their superior numbers cleared the entire surrounding sector of life before the xenos made planetfall upon Baal and her twin moons. The first nineteen waves, each larger than the last, were driven off at great loss to the Blood Angels and their successor allies. Five Chapter Masters fell in that bitter fighting, three in the Battle at the Dome of Angels alone. The Tyranids began the process of absorbing all biomass from Baal and its moons, absorbing even the radiation-poisoned deserts of Baal Secundus. With their defences in ruin and Baal's moons stripped and broken, the remaining Space Marines retreated back to the rubble of the Blood Angels' sprawling fortress-monastery. There, they prepared for a last stand as the next wave swept downwards. Doom, it seemed, had at last come to the Sons of Sanguinius.It was then that the Great Rift cracked open the galaxy in the wake of the fall of Cadia to the 13th Black Crusade, and the withered Baal System was blasted by the aetheric storms. Although no further attack waves came from the Leviathan Hive Fleet, not a single Imperial defender remained alive upon the last moon, Baal Prime. On Baal itself there were already enough Tyranids to destroy the Imperial troops many times over. Even with no chance of victory, Commander Dante led his troops, each fighting retreat seemingly more hopeless than the last. The empyrean energies spilling from the Great Rift caused time itself to pass strangely on Baal. The combatants may have faced each other for mere solar days, or Terran years may have passed in the rest of the galaxy.As the final perimeter was broken, the stars reappeared. Looking skywards, the Tyranids on the surface of Baal sought contact with their hive fleet, but it was gone, replaced by a newly arrived Imperial fleet. Like an angel of vengeance came Roboute Guilliman and his Indomitus Crusade. After many more battles, Baal was finally cleared of the xenos threat. A great rebuilding of both world and Chapter was undertaken, for the Blood Angels and their successors were sorely needed elsewhere in the beleaguered Imperium. Guilliman brought with him Primaris Marine reinforcements to replenish the ranks of the Blood Angels and the Sanguinary Brotherhood. Guilliman named Dante as the regent of the Imperium Nihilus and charged him with doing what he could to reclaim taht half of the Imperium for the Emperor. What became of the Leviathan is a mystery, although a clue was found upon the now-barren moon of Baal Prime. Xenos skulls were piled impossibly high in the much-reviled, eight-pillared symbol of one of the Blood Angels' most terrible and ancient nemeses: the Bloodthirster Ka'Bandha and his army of Khornate Daemons.