Attack on the Zeta Hydronis Secundus system
During the Forerunner's war with the Flood, Flood forces attacked a Forerunner star system inhabited by Miners. The Flood was initially held back, but with the assistance of the Gravemind, the parasite eventually prevailed.
During the Flood's conquest of the galaxy, the parasite arrived at what would be known by the UNSC as the Zeta Hydronis Secundus system. Protected by layers of hard light and exotic matter, and fitted with energy projectors, the system's planetoids were considered impregnable. Due to the advanced defenses, the Flood's initial attack failed, however, the Forerunners' victory was short-lived, when the Gravemind itself turned an infinitesimal portion of its immense intelligence to bear on the problem.
Grasping impossible filaments buried beneath reality by the long-vanished Precursors, the Gravemind pulled at strands that twisted and warped real space. Walls made of collapsed starmatter cracked and shattered, entire fleets of kilometer-long warships tasked with defending the system vanished in flares of light, and colony planetoids were ripped apart. With the Miners' defenses compromised, the Gravemind poured billions of combat forms onto the surfaces of the colony worlds and into the Miners' installations. Those that survived the initial onslaught could only activate failsafes and await their deaths at the hands of the parasite.
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