The Genesis War is a war that occurs in the world of Final Fantasy VII. It forms most of the plot of Crisis Core -Final Fantasy VII-, and is a conflict in which Genesis Rhapsodos goes to war with Shinra Electric Power Company using copy technology and defected SOLDIER members to create an army of Genesis Copies. The war started on October εуλ 0000 and most fighting ceased εуλ 0002. Genesis himself was defeated in September εуλ 0007.
In late summer of εуλ 0000, Genesis is wounded in a sparring match with Sephiroth and Angeal Hewley. The Shinra scientist Dr. Hollander sees to his injury, and during the recovery Genesis learns of his origins as a member of the Jenova Project's Project G, and that the wound has triggered his genetic degradation due to his imperfect inheritance of Jenova's abilities. Hollander manipulates Genesis into warring with Shinra, promising a cure for his condition. Hollander approaches the director of SOLDIER, Lazard, who has his own history with Shinra, and he agrees to secretly fund Hollander and Genesis.
A few months before the end of the Wutai War, Genesis, Hollander, and a large number of 3rd and 2nd Class SOLDIERs go missing in the Mass Soldier Desertion Incident. The group went to Banora, where Hollander uses his knowledge of Jenova to begin producing Genesis Copies. The defected SOLDIER members were implanted with cells taken from Genesis, granting them enhanced physical capabilities and Genesis's facial appearance. Banora became a base for the rising Genesis Army, most of the civilians fleeing the area as Genesis and Hollander built up their forces.
During the attack on Fort Tamblin, Genesis sends a force of Genesis Copies to Wutai to contact Angeal and persuade him to join their cause. Angeal never returns from Wutai, and Shinra declares both him and Genesis killed in action, presuming Angeal to have allied with Genesis. In truth, Angeal never committed to either side, torn between his conflicting loyalties and helping either side as he struggled to come to terms with the events and his past.
Throughout εуλ 0001, Sephiroth, Zack Fair, and the rest of Shinra and SOLDIER combat Genesis's forces across the globe. The Genesis Army's boldest move is an attack on Midgar, infiltrating the Shinra Headquarters there and narrowly being stopped from capturing Professor Hojo. Optional missions allow Zack to combat the Genesis Army on various fronts as they attack Shinra factories and steal Materia, weapons and robots from Shinra. In turn, the missions include Zack destroying Genesis Army strongholds and bunkers and tracking down detachments sent to various locations, including the Great Cavern of Wonders. However, the missions don't influence the main story.
With Banora destroyed by Shinra, the Genesis Army relocates to a new base, a Mako Reactor near Modeoheim. Zack is sent to the reactor and confronts Genesis, who is fed up with Hollander's failures to cure him and declares to find a new path. Zack battles Genesis and sends him falling into the reactor core. Zack finds Angeal who is unable to handle the truth of what he is, and he attacks Zack. Zack kills Angeal, who grants Zack his Buster Sword. Hollander is captured by Shinra forces, and the Genesis War is apparently over. A few months later Lazard's hand in helping Genesis and Hollander is revealed and he leaves the company.
In the summer of εуλ 0002, the Genesis Army resurfaces, attacking around the world, and Hollander is freed from Shinra's imprisonment by Genesis Copies. Genesis survived Modeoheim, and his copies now target Mako Reactors to find Jenova, Genesis believing her cells are the key to curing him. Sephiroth and Zack are dispatched to Nibelheim to investigate the town's Mako Reactor, which is where Jenova is held. Genesis finds them and tells Sephiroth about the Jenova Project and asks for his help in finding a cure, but Sephiroth refuses. The Nibelheim Incident occurs a week later, Sephiroth is declared MIA and Zack is taken into custody as a test subject, imprisoned in Shinra Manor. The actions of the Genesis Army over the next few years are unclear.
In εуλ 0007, Zack breaks free of the Manor with an infantryman who was at Nibelheim, Cloud Strife, and flees from Shinra's forces. Genesis tracks down Zack and takes some of his hair to allow one of his copies to feed on, consuming Zack's Sephiroth Cells that had been implanted into him after Nibelheim. The copy mutates into a monster, and Genesis and Hollander, who is now himself infected by degradation due to Project G cells, believe it to be because Zack was in SOLDIER, and so his S-Cells are not pure. The two attempt to take Cloud, but Zack and Lazard, transformed into an Angeal Copy and driven by Angeal's will to aid Zack, protect Cloud and Zack kills Hollander.
Realizing Genesis has always had a Banora White when he appears, Zack returns to Banora, discovering the underground caverns where Genesis has continued his operations. Zack defeats Genesis in a final duel, and the unconscious Genesis is retrieved by Deepground when Zack leaves the area. With Genesis's defeat, the Genesis Army apparently disbands and the war comes to an end.
Genesis's actions during the war aided in causing the Nibelheim Incident, inadvertently turning Sephiroth into the worst enemy the planet had faced since Jenova. It also lead to Zack going rogue and his eventual death.
The loss of their most decorated members damaged SOLDIER's reputation and the group never reached the same heights of public adoration as they did with Sephiroth, Genesis and Angeal in the media spotlight. Lazard's defection reduced SOLDIER's influence within the company and with no replacement Director named in Crisis Core, the organization apparently compressed into the Public Safety Maintenance Department under the command of Heidegger.