An attack of ignorance was what the Great Houses used to punish the renegade Presidency by simply ignoring them.
The Great Houses's Homeworld was a metaphorical eye that maintained the framework of history by observing it and keeping its causal connections and time-structures in check. If this "eye" failed to see a part of the Spiral Politic, that part would be ravaged by the random probability-forms of the unformatted universe, ungoverned by the certainty of history.
When the renegade Presidency on Dronid was ignored by the Homeworld, a front of protospace and anti-history tore apart their powerbase and ate through the culture of the local population, reducing them from industrial city-states to terrified, insular communities ripped apart by the colliding time-states.
Early in the War, the Great Houses attempted to ignore an enemy world into submission, but the attack had no effect on the target, suggesting that the enemy also had an "eye" to oversee history. (PROSE: The Book of the War)