But Symat understood that the beauty of the weapons clouds wasn’t their point. Their purpose was lethality. The whole of the Saturn system was a fortress. And it was all because of the Ascendents.
When the vast retreat of man had begun, even when only the most remote of colonies had yet been evacuated, the undying with their eerie far-flung prescience had planned the end game. Before the siege of Earth itself began, it would be necessary to make a stand.
Saturn had always been a military stronghold. As long ago as the Exultants’ heroic effort to win the Galactic Core, huge war machines had been buried in the planet’s deepest clouds, ready to leap to the defence of Earth if any foe dared attack the capital planet. These brooding machines, self-maintaining, self-enhancing, became known as the Guardians.
Now, as a far more formidable foe gathered, the Ascendents turned to Saturn once more. Earth itself was to be corralled with gravitation and brought out here, to circle on the rim of Saturn’s mighty gravity well, where it could be protected. And the war machines under those clouds, already powerful, were enhanced with the accumulated learning of a million years of interstellar war.
-Resplendent, "The Siege of Earth"