Following the deployment of the virulent disease better known as the Omnius Scourge, and the subsequent decimation of many worlds in the League of Nobles, the League discovered that Omnius Prime was planning to follow up the disease with a quick military strike against Salusa Secundus, to effectively decapitate the coalition of free humans.
Cogitor Vidad suggested that Salusa Secundus should be evacuated. Supreme Commander Vorian Atreides convinced the League to use spacefolders to launch a broad and coordinated nuclear strike against all Synchronized Worlds while this would happen. Corrin would be the last target, and by the time the robotic fleet arrived on Salusa, they would be mindless without the existence of Omnius.
Spacefolding spycraft secretly darted back and forth from Corrin, bearing regular reports on the progress of the giant machine fleet; other scouts bore the news among the League Worlds and calling the survivors to action. These suicidal missions were mostly manned by Martyrists who longed to die for the Jihad and were considered expendable.
Vorian appointed Faykan Butler and Abulurd Harkonnen to evacuate the planet while pulse-atomics were constructed and new nuclear warheads were being manufactured frantically on all League industrial planets. Kolhar shipyards supplied the Jihadi capital ships with spacefolder engines. To reduce the spacefolding hazards Vorian Atreides secretly ordered Norma Cenva to install the last computerized navigation systems she had kept after they were banned.
Vorian also conceived an innovative weapon: satellites armed with pulse-scrambler transmitters. They would be set around Corrin, preventing therefore an Omnius update gelsphere to leave the planet during the final assault.
The whole fleet, 1080 ships in all, was divided into 90 battle groups of 12 major vessels each, each group with its own list of targets. The Ballistas were loaded with hundreds of kindjal bombers (piloted by skilled veterans or by rapidly trained Martyrist volunteers) containing pulse-atomic warheads.
The advantage of the Purge was the spacefolding technology, believing that no Omnius ship would be fast enough to notify Omnius about the attacks. However Cogitor Vidad, when he told Omnius about the Titans' hideout on Hessra, he also mentioned the plans of the Purge.
Immediately, Omnius dispatched superfast "burnout" probes with enormous engines. They accelerated as fast as possible, overtaking the bulk of the fleet, transmitting Omnius' new orders and reprogramming the ships. The ships changed course and the fastest of them came back to Corrin at extreme speed, pushing their systems so furiously that some were overheated and damaged en route. Meanwhile, Omnius' industries produced weaponry and robotic fighters.
The attack, stretched the League's resources to their limit, and begun as soon as scouts reported that Omnius' extermination fleet left Corrin for Salusa Secundus. The first planetary systems would be lesser machine worlds, primarily military strongholds and resupply points; one of the first targets of Vorian Atreides was the Synchronized World in the Yondair system. Some of the worlds were unexpectedly fortified and had put up heavy resistance. Five of the groups had failed at specific targets, which would necessitate a second offensive to the same coordinates. When about 1/3 of the 543 worlds were destroyed, the fleet would redirect to the more important worlds, such as Quadra.
Inspired by the update method of Omnius, Vorian Atreides devised a network of scouts and messengers; flurries of the small ships bearing reports and records converged at established rendezvous points, dispatching buoys with their detailed data and logs. Other scouts from other battle groups would retrieve and disseminate them, keeping the commanders apprised of the progress.
One by one the Synchronized Worlds were wiped of their Omnius incarnations, as well as most (and in many cases all) biological life. The human slaves of those worlds would never be freed and were obliterated along with the machines, as collateral losses. Near the end of the operation, estimates indicated that over a billion slaves and trustees perished during the attacks.
The biggest problem of the Purge fleet were the hazards of the spacefolding travel. Each space jump would result in a percentage loss of some ships which vanished now and then, one after the other. One of the 90 groups was left with 4 ships after some jumps, which eventually also vanished in a single space jump, and only two of their fast messengers had survived to deliver their fateful reports. Quentin Butler's group was left with only 6 ship before 3 of them were vanished in a single jump, forcing him with the remaining 3 to join Vorian Atreides' group.
Because of the spacefolder accidents, 266 capital ships remained, out of the initial 1080. These were converged into one single large battle group and headed for the final and most important target: Corrin
When the Purge fleet arrived near Corrin the first machine ships had already returned and the Jihad commanders realized their forces were not enough. Quentin Butler volunteered for a suicidal strike but was prevented by Vorian. The rest of the machine fleet was returning. As a last measure, they launched the scrambler satellites around the planet. When all of the machine fleet was positioned in defense above Corrin, Vorian ordered activation of the satellite network. As a result, no machine could leave without damaging itself and Omnius remained trapped, being able only to reinforce his existing forces, diminishing the resources of the now-isolated planet.
The Purge fleet remained there, also reinforced in the following years, blockading the planet and looking for weak spots to start an eventual strike.
Though the Great Purge failed in its ultimate goal, it proved a crucial blow in the war against the Synchronized Worlds, and ended in Corrin being blockaded, and Omnius Prime effectively imprisoned. Grand Patriarch Xander Boro-Ginjo officially ended the Jihad. Following several increasingly desperate attempts to break free it also formed the foundation of the later Battle of Corrin decades later.
In the following years, philanthropist Porce Bludd asked the League of Nobles to support and receive the human survivors of the former Synchronized Worlds, but his request got a negative response. With his old friend Quentin, they traveled on Bludd's private ship and supplied the re-emerging primitive communities with food, medicine and tools to ease their lives.