Attack on Zero

The Attack on Zero took place in 1976 and was an event in which Zero, the founder and leader of Cipher, was attacked by his Executive Officer, Skull Face, who at the time commanded Cipher's strike force XOF.

Prelude

Following Paz Ortega Andrade's failure to coerce Big Boss into rejoining Cipher during the Peace Walker Incident, she was captured and taken to Camp Omega in Cuba, where she was subjugated to interrogation and torture regarding Zero's location.

In March 1975, Chico, having heard of Paz' survival, recklessly decided to rescue Paz by going to the facility but was captured, tortured, and interrogated for information about Militaires Sans Frontières' staff, Mother Base, and Metal Gear ZEKE. After a while, Chico gave Skull Face what he wanted. When Paz realized that Skull Face was going to kill Zero, albeit for himself, she gave up Zero's location in Hell's Kitchen 10th Avenue in New York City and how Zero controlled the information to divert suspicion of his hiding place.

Having gotten the information he needed from Chico and Paz to strike at both Big Boss and Zero, Skull Face advanced his plans, by striking Big Boss first. Having arranged a fake nuclear inspection with Huey Emmerich, Skull Face initiated a Trojan Horse operation, which was a success; MSF and Mother Base were destroyed. Although Big Boss survived, he ended up in a coma. As punishment, Skull Face was reassigned to Africa but remained Zero's XO.

Attack on Zero

In 1976, Skull Face recovered the winged dagger lapel pin which belonged to a soldier in the SAS who both Zero and The Boss knew. Still carrying it at the time of her death in Tselinoyarsk during Operation Snake Eater, which Skull Face was also involved in. Having recovered the lapel pin from Tselinoyarsk from The Boss' body, Skull Face kept the real lapel pin and made a convincing replica which he coated with a form of the vocal cord parasite and sent it to Zero.

Having sent the fake lapel pin, Zero called Skull Face from New York, having supposedly gotten what he wanted. Skull Face inquired about the back of the lapel pin to which Zero accidentally pricked his finger, unknowingly infecting himself which slowly began to take effect.

Zero talked about the owner of the lapel pin, who died on December 30, 1941, whose body was never recovered and how it effected both him and The Boss, who vowed to never let it happen again, calling the unknown soldier his and The Boss' brother in arms.

Skull Face, wanting to talk to Zero, brought up that Kazuhira Miller had been found in Rhodesia. Zero, who believed that Miller would make a mistake soon, was unconcerned. Skull Face then moved on to how he could be more useful to Zero, as Central Africa's Angola-Zaire border region was rich with biological resources, and that an old plan could be brought back into action.

Zero dismissed his predecessors' daydreams and said that the vocal cord parasites were no more than an excellent test for reverse evolution. Favoring genetics technology, Zero said that the vocal cord parasites were too clumsy as they had the potential of destroying the human race; soon they would be able to target specific individuals. Zero then talked about how once the Cold War was over, Cipher's enemies would blend into the electronic network which would soon spread around the world. Skull Face objected saying that people needed their enemies, with Zero understanding that the result was ethnic conflict, religious strife, and terrorism and that deterrence was irrelevant.

A solution to this, as Zero pointed out, was an information control to create context to maintain balance. Skull Face was skeptical of this plan and suggested the use of the parasites. Zero dismissed this suggestion; with Zero's plan, the world that The Boss envisioned would become a reality. 

Skull Face, getting slightly more aggressive, said that he had lost his face forever. Zero replied that a soul that could communicate dismissed the need for a face. Dropping his façade, Skull Face said he didn't intend to hide behind Zero's technological veil. He revealed that his skull was in the open so that he would never forget what he had lost, declaring that the chain of retaliation would bind the world together as one.

Suddenly, Zero groaned in pain, as the parasites had taken effect. The alarm was raised, but Skull Face taunted that it was too late for the doctors to extract the parasites. Zero asked how Skull Face found him. He then answered his own question, realizing that Skull Face had gotten his location from Paz.

Skull Face further taunted the pained Zero by saying that it was time for the latter to step aside, not content with killing Zero. He had bought him little time before Zero entered a permanent vegetative state. Skull Face stated that Zero was wrong about what The Boss wanted. Zero stated that Skull Face was no different from Big Boss and no one understood what she wanted. Skull Face replied that included Zero. Skull Face also stated that he was the only one who understood what The Boss wanted and he would take it from here.

As a parting shot, Skull Face revealed that the lapel pin he coated with the parasites and sent to Zero was an elaborate fake, and that he would keep hold of the real lapel pin while continuing The Boss' work. Zero called out for Big Boss before he collapsed.

Aftermath

Following this, Skull Face would eventually take over Cipher. Zero visited the comatose Big Boss and Venom Snake at the Dhekelia SBA Memorial Hospital in 1977, before going into hiding for good and entering a permanent vegetative state.