Abimael Guzmán, the founder and leader of the Shining Path guerrilla movement, which spread terror across much of Peru in the 1980s and ’90s, died on Saturday in Peru. He was 86.

Mr. Guzmán died in a maximum-security prison in the Callao naval base in Peru, where he was serving a life sentence, prison officials said. They said he died of health complications but did not specify an exact cause.

An estimated 70,000 Peruvians were killed during the decade-long peak of the Shining Path insurgency, at least one-third at the hands of guerrillas. Shining Path advocated a violent reordering of society away from the vices of urban life. Its leaders echoed Cambodia’s Khmer Rouge with warnings that “rivers of blood” would flow after their victory, and that as many as one million Peruvians might be put to death.

Shining Path was almost entirely Mr. Guzmán’s conception, and for a time he seemed poised to seize power in one of Latin America’s most important countries. His avowedly Maoist movement was one of the most violently radical in the hemisphere’s modern history, and his fertile mind and extraordinary powers of persuasion laid the basis for an intense personality cult.

Like many of his generation in Latin America, Mr. Guzmán was thrilled with Fidel Castro’s revolutionary victory in Cuba in 1959. Later, however, he came to scorn Castro, the Soviet Union and even moderate factions in China.

Mr. Guzmán visited China several times. He came away with the vision of a Peru without money, banks, industry or foreign trade, where everyone would be a landholder and live from barter.

Both of Peru’s main Communist parties expelled him, but he developed a devoted coterie of students and professors.

“He was a very charismatic teacher, with a florid rhetorical style that really attracted students,” the political scientist David Scott Palmer said in 2013. “He became so strong partly because of 17 years of preparation, and partly because government missteps created conditions favorable to revolution.”

(Professor Palmer, who as a Peace Corps volunteer in the 1960s shared an office at the University of Huamanga in Ayacucho, Peru, with Mr. Guzmán, a faculty member, died in 2018.)

Shining Path carried out its first violent actions in 1980, including the bombing of polling places and the takeover of town halls in remote villages. One morning in December, people in Lima, the capital, awoke to the sight of dead dogs hanging from dozens of lampposts. Around the neck of each was a placard with a slogan referring to factional struggle within the Chinese Communist Party.

This was the first sign of the phantasmagorical savagery that was about to descend on Peru. Mr. Guzmán, calling himself President Gonzalo, proclaimed himself the “Fourth Sword of Communism,” after Marx, Lenin and Mao. He preached “Gonzalo Thought,” which he said would bring the world to a “higher stage of Marxism.”

“When the Shining Path took up arms, the attempt seemed a doomed effort to graft the Chinese experience onto the entirely different Peruvian culture,” the Peruvian journalist Gustavo Gorriti wrote. “To most people in Peru, including the legal left, the movement seemed to be a crazy sect, hopelessly divorced from reality.”

But Mr. Guzmán’s fighters waged a spectacularly successful military campaign that brought large parts of the country under their control. Terror and assassination were favored tactics. The conflict spread from rural areas to Lima, where supplies of water, electricity and food became unreliable.

Bombs exploded in movie theaters, restaurants and police stations. Kidnappings were rampant. Notices appeared on walls warning civilians to flee. Thousands did. The economy, already in dire shape because of poor political leadership, plunged toward chaos.

Shining Path tried to find a base among Indigenous people whose needs had long been ignored by Peru’s elite, though many Indigenous people were also victims of the insurgency. Part of Mr. Guzmán’s strategy was to draw the nation’s army into bloody reprisals, revealing its “fascist entrails.”

Military repression was indeed fierce. Soldiers killed many civilians and terrorized Indigenous regions, driving many to support the rebels.

After several years, the government changed course. It withdrew some abusive units, gave soldiers rudimentary human rights training and began civic action programs.

Two figures associated with the campaign against Shining Path, President Alberto Fujimori and his intelligence director, Vladimiro Montesinos, were later given long prison sentences after being convicted of engaging in corruption and sponsoring death squads.

On Sept. 12, 1992, members of a special police unit dedicated to tracking Shining Path leaders closed in on a home in a well-to-do Lima neighborhood and captured Mr. Guzmán. He appeared in a military court wearing a black-and-white striped prisoner’s uniform. Hooded judges found him guilty of terror crimes and sentenced him to life imprisonment.

In 1993, Mr. Guzmán appeared several times on Peruvian television and called on Shining Path fighters to give up their arms. Most did, and the rebellion faded.

Manuel Rubén Abimael Guzmán Reynoso was born on Dec. 3, 1934, in the town of Mollendo, on Peru’s southern coast. His father, who had six children with three women, won a prize in the national lottery and sent him to a Roman Catholic high school and to college.

After earning degrees in law and philosophy, Mr. Guzmán joined the faculty at San Agustín National University in the mountain town of Arequipa. He became director of its teacher training program, which attracted students from Indigenous villages.

Mr. Guzmán is not known to have had children. As a young man, he married Augusta La Torre, daughter of a Communist Party leader in Ayacucho. Known as “Comrade Norah,” she became the second in command of Shining Path. She died in 1988 under mysterious circumstances.

In 2010, when Mr. Guzmán was 75, the authorities gave him permission to marry Elena Iparraguirre, who had replaced Comrade Norah as the No. 2 Shining Path leader and was also serving a life sentence on terrorism charges. They continued to be held in separate prisons.

Mr. Guzmán was given a second trial, before a civilian court, after his military trial was found unconstitutional. In 2006 it found him guilty of aggravated terrorism and murder, and affirmed his life sentence. At the trial, he shouted what might have been his last public words.

“Long live the Communist Party of Peru!” he cried, waving a fist above his head. “Glory to Marxism-Leninism-Maoism! Glory to the Peruvian people! Long live the heroes of the people’s war!”

Julie Turkewitz, Elda Cantú and Mitra Taj contributed reporting.