Big Boss defeats old Vietnam comrade Python in battle. Big Boss encounters Frank Jaeger, now a member of FOX, again in battle and rescues him. Big Boss and Roy Campbell meet Elisa, and they discover the plans for the ICBMG.
The San Hieronymo Incident ends. Big Boss successfully destroys Metal Gear RAXA, with the help of Nikolai Stepanovich Sokolov. Cunningham reveals that he is actually serving the United States Department of Defense to try and discredit the CIA, and is killed in a fight with Big Boss. Gene, leader of FOX, fatally wounds Elisa. With her last breath, Elisa foresees that one of Big Boss's sons will "bring the world to ruin", while the other will "save the world." Big Boss proceeds to kill Gene, who gives him the funds he had amassed for "Army's Heaven." He later manages to destroy the ICBMG before it could activate after launching.
Major Zero forms the Patriots, dedicated to reuniting the world in honor of The Boss's final wishes. Ocelot joins the unit, but stays in the Soviet Union as an informant. Sigint, Para-Medic, and Big Boss make up the rest of the organization. Major Zero proceeds to turn Big Boss into an idol and hero, to lead the world as a messiah-like figure.
The Nuclear Non-Proliferation Treaty is signed by America, the Soviet Union, France, England, and China, the nuclear powers at the time.
Yukio Mishima commits suicide during a failed coup d'état at the Japan Self-Defense Forces' eastern command HQ, in an attempt to restore the divinity of the Emperor. His questioning the status quo of the JSDF influences the later resignation of soldier Kazuhira Miller.
The ABM Treaty is signed by the United States of America and the Soviet Union on the limitation of the anti-ballistic missile (ABM) systems used in defending areas against missile-delivered nuclear weapons.
The Munich Massacre occurs when the terrorist organization Black September holds 11 Israeli athletes hostage during the Olympic Games, eventually killing them. As a consequence of the incident's tragic mismanagement, the GSG 9 counter-terrorism force is created.
The Nicaraguan earthquake occurs, resulting in the decimation of Managua, with 5,000 killed, 20,000 wounded, and 250,000 homeless. Despite international aid and relief efforts, Nicaragua did not recover due to the Somoza regime pocketing the relief funding for themselves.
Working with the Colombian Army, Militaires Sans Frontières ambushes a guerrilla unit led by Kazuhira Miller. Miller, the only survivor, is captured and eventually recruited into MSF after Big Boss earns his respect, becoming second in command.
1973 Chilean coup d'état. The socialist government of the Chilean President Salvador Allende was overthrown by the Chilean military, led by General Augusto Pinochet, in a coup d’état supported by the CIA.
Gerald Ford meets with Leonid Brezhnev to negotiate SALT II at Vladivostok. MSF stops Peace Walker in Nicaragua, preventing a nuclear attack with assistance from Sandinistas under Amanda Valenciano Libre and The Boss AI. Peace Sentinel leader Hot Coldman dies and secret collaborator Gálvez, a.k.a. Vladimir Zadornov, is captured by MSF.
Paz, a.k.a Pacifica Ocean, hijacks ZEKE and offers Big Boss the choice to rejoin Zero's organization, Cipher. The offer is refused and Paz prepares to launch a nuclear strike to frame MSF, forcing Big Boss to disable ZEKE. Paz falls into the ocean and disappears.
MSF, via an undercover agent, learn of classified intel that pertains to Cipher. They immediately head to the Naval Prison Facility to retrieve the information, which is included on a cassette tape. The information on the tape reveals the existence of a Cipher-affiliated individual known only as Skull Face.
A group of FSLN guerrillas seize the home of a former government official and took as hostage a handful of leading Nicaraguan officials, many of whom were Somoza relatives. The guerrillas succeed in getting 14 Sandinista prisoners released from jail and flown to Cuba along with the kidnappers. They achieve recognition as a representative of anti-Somoza sentiment.
Chico is captured, imprisoned and tortured by XOF after attempting to rescue Paz at the U.S. naval base in Cuba. He gives XOF commander Skull Face information on MSF, after being forced to watch Paz's torture.
XOF plant C4 explosives on MSF's Mother Base. Under Skull Face's orders, Chico sends out an SOS transmission that is picked up by MSF. Despite suspecting a trap, Big Boss commences a lone infiltration of the prison site. Paz is manipulated by Skull Face into revealing Zero's location, before being drugged and implanted with two timer bombs.
Big Boss infiltrates Camp Omega and extracts Chico and Paz by chopper. XOF attacks Mother Base, during which Miller is extracted from the doomed facility. Paz awakens and jumps from the chopper to prevent the implanted bombs destroying it, but the detonation sends the helicopter into the path of another. Chico, the helicopter pilot, co-pilot and another soldier are killed. Big Boss, Miller and a medic are injured.
The three survivors are taken to a medical facility in Colombia where Big Boss and the medic fall into comas. Word of the incident reaches Zero and he hides Big Boss and the medic in a Cyprus hospital to protect them, under Ocelot's care.
Zero realizes he will eventually become a vegetable, but buys himself a few years thanks to his connections and resources. He then decides to create an A.I. system that will survive him and carry on his will - a system that would later evolve into the Patriots. The groundwork for the advanced A.I. is designed by Dr. Strangelove.
The Mozambican Civil War begins, between the ruling party, the Front for Liberation of Mozambique (FRELIMO), and the Rhodesian/South African-funded Mozambique Resistance Movement (RENAMO). Frank Jaeger would later return to Mozambique and participate in the conflict as a RENAMO soldier, ultimately being rescued by Big Boss after suffering torture.
Prime Minister of Grenada Sir Eric Gairy lobbies the UN to create an agency or department to study UFOs and extraterrestrial life, influenced by magazine photos of the Chrysalis, originating from Chico.
The FSLN overthrows Somoza in an armed uprising, helping realize the Nicaraguan Revolution. Somoza defects in the aftermath, ensuring the Nicaragua Revolution comes to fruitition, and is assassinated the following year.