: High Charity suffered severe structural damage while escaping from the battle
: around Installation 05. The Flood was enacting repairs and overlaying
: fleshy growths over the superstructure, but had insufficient time and
: resources to complete the repairs. High Charity would have broken apart
: attempting to enter the Voi Portal. If tidal forces did not split her
: asunder, the various stresses from atmospheric entry would do the job.
: Even the process of exiting slipspace would have pushed the dead city to
: its limits. Leaving a rear guard in the form of an infected Earth was a
: worthy objective, but attaining it would strand the Gravemind short of the
: Ark.

: But the Gravemind is clever, and possesses the collective technical knowledge
: of an extinct galactic civilization. The back-up slipspace drives on High
: Charity were modified and upgraded during the journey to Earth, and
: Gravemind entered the Voi Poortal directly from Slipspace.

: A halfhearted attempt was made to establish itself on Earth, but most of the
: Flood-captured warships were sacrificed around Installation 05 in the
: defense of High Charity. One was sent ahead to Earth as a scout, and what
: few remained were needed to escort High Charity to the Ark. The invasion
: took the form of dropships and civilian vehicles that were shunted out of
: Slipspace in Earth's orbit, to be quickly intercepted by Earth's remaining
: defenses and those Separatist ships too damaged to accompany Rtas 'Vadum's
: fleet.

That reminds me that I've always found it an interesting leap in regards to the Delta Halo situation where we leave it in Ghosts of Onyx, and then it showing up as a Flood hive in Halo 3. We know the Covenant were apparently fairly effective in stopping the Flood from leaving the Halo ring—but leaving High Charity would have been a fairly big oversight. Did they attempt to destroy High Charity to stop its infestation?