JOHANNESBURG — When Zimbabwe’s generals moved against President Robert Mugabe on Wednesday, their action foreshadowed the potential end of more than just one political career. It echoed across a continent where the notion of the “big man” leader is defined equally by the lure of power in perpetuity and the risk that, one day, the edifice will crumble under the weight of its own decay.

Mr. Mugabe, 93, who took power upon independence from Britain in 1980, is the only leader Zimbabwe has known. He has suppressed perceived threats to his dominance, often brutally, and maneuvered with guile to outflank his rivals. Decades after the furling of Britain’s union flag, he waved his liberation credentials with such skill and frequency that he stood as an emblem, however flawed, of Africa’s yearning to be free of outside control.

Viewing himself as Africa’s true statesman, Mr. Mugabe, even in his 90s, flew regularly to diplomatic gatherings on the continent, including mundane ones in which he was sometimes the only head of state present. Though he is despised in the West and by many Zimbabweans, many Africans view him as a living, historic figure, inspiring diplomats and officials to stand and applaud his speeches criticizing Western powers.

In the end, though, his deft touch deserted him as he weighed the question looming over the end of his regime: who would succeed him. By favoring his polarizing and politically inexperienced wife over his powerful vice president, whom he fired last week, Mr. Mugabe overestimated the loyalty of the military and security elite who took him into custody early Wednesday in what appeared to be a coup.

Mr. Mugabe’s family became his blind spot. He miscalculated the fierce anger that their unrestrained behavior caused in his nation, now suffering through another period of deep economic crisis. Though active in politics for only a couple of years, his wife, Grace Mugabe, 52, made it increasingly clear that she wanted to succeed her husband. “If you want to give me the job,” she told her husband at a gathering this month, “give it to me freely.”

Mr. Mugabe’s sons, who are in their 20s, have added to the anger among Zimbabweans by regularly posting pictures of their lavish lifestyle and partying on social media sites. Last week, a video emerged showing Mr. Mugabe’s younger son, Bellarmine Chatunga, pouring Champagne over an expensive watch on his wrist. On his Instagram feed, he wrote, “$60 000 on the wrist when your daddy run the whole country ya know!!!”

Whatever happens now, experts and analysts said, the days of Mr. Mugabe’s unrivaled hold on Zimbabwe seem at an end. That is a message that offered an unpalatable reminder to leaders who have clung to power for decades in Africa — from Equatorial Guinea and Cameroon to Eritrea and Uganda. Even the wiles of a politician of Mr. Mugabe’s stature do not guarantee success to those who seek to extend their tenure indefinitely.

In Harare, Zimbabwe’s capital, Mr. Mugabe’s precise fate remained uncertain on Wednesday, but many Zimbabweans referred to his house arrest as the end of his unchallenged rule and the start of a new chapter in their lives.

“I’m happy now,” said Donald Mutasa, 37, who was born at the start of the Mugabe era. “I feel like we have just gained independence. I am hopeful we are walking into a new Zimbabwe.”

Mr. Mugabe rose to and remained in power by assiduously courting the generation of former fighters and politicians who had been with him in the exiled days of what he and other Shona speakers called the Chimurenga, the revolutionary struggle to end white rule and British colonialism.

During the liberation war, in which he was never actually a military commander or fighter, Mr. Mugabe frequently cited the Maoist principle that political power flows from the barrel of the gun, an adage that now seems to have been turned against him.

Patrick Smith, the editor of the Africa Confidential newsletter and The Africa Report magazine, said that since Mr. Mugabe made the decision to break with his former vice president, Emmerson Mnangagwa, and other liberation leaders, “there was not going to be a way back.”

Mr. Mugabe could still be “a fig-leaf for a transition” in the weeks ahead, Mr. Smith said, but a return to his erstwhile dominance seemed unlikely.

As Mr. Mugabe’s health declined and his wife grew increasingly powerful, the dividing line in Zimbabwean politics was soon drawn between the so-called Generation 40 of younger people surrounding Grace Mugabe and the older Zimbabweans who fought in the liberation struggle and have amassed the spoils of power.

Zimbabwe’s business, political and military elites are known for the farms, villas, cars and bank accounts they have accumulated since independence, in marked contrast to ordinary Zimbabweans who have fled the country or lived in perilous economic times, facing the unemployment and hyperinflation that made many dependent on remittances from family members in exile.

Through all of it, Mr. Mugabe remained in power. In his earliest days, he had modest roots as the Catholic-educated son of an absentee father in the rural area around Kutama, where he was born on Feb. 21, 1924. His father abandoned the family when he was 10. He was known as an earnest and solitary child.

In his 20s, though, his political ambitions crystallized between 1950 and 1952, when he attended the University of Fort Hare, an institution in South Africa that became an incubator for some of the continent’s most fabled nationalist leaders, including Nelson Mandela.

“Marxism-Leninism was in the air,” Mr. Mugabe once said in an interview before Zimbabwe’s independence. “From then on I wanted to be a politician.”

It was a time of passions churning across Africa as more and more nations achieved independence — a phenomenon that alarmed the white minority, many of them settlers from Britain, who called the colony of Southern Rhodesia home. In 1965, led by Prime Minister Ian Douglas Smith, the white minority declared its own independence from Britain, though it was not internationally recognized.

For Mr. Mugabe and many others, the white authorities represented the enemy. He was jailed, and his bitterness toward his adversaries deepened while in detention when his only child at the time died in Ghana. The white authorities, calculating that Mr. Mugabe would not return if released, refused to allow him to attend the funeral.

When he was, in fact, released in 1975, he soon slipped across the border into Mozambique, which had just achieved independence from Portugal. The country was to become the base for Chinese-backed guerrilla fighters loyal to his movement, the Zimbabwe African National Union. Mr. Mugabe, who was never seen to bear arms, struggled initially to secure the fighters’ support.

By the time a cease-fire was declared in late 1979 at a peace conference in London, some 27,000 people had died, most of them from the black majority.

Mr. Mugabe was elected prime minister just before independence from Britain in April 1980. At the time, he struck a conciliatory tone with his former adversaries, but some people in his entourage said he would have preferred the war to have continued toward a military victory rather than a negotiated settlement.

From the moment he took office, Mr. Mugabe worked assiduously and sometimes bloodily to cement his rise to power. In the early 1980s, soldiers from his North Korean-trained Fifth Brigade swept through Matabeleland, the home base of a rival from the liberation struggle, Joshua Nkomo, killing thousands of people, mostly civilians.

At the same time, Mr. Mugabe greatly enhanced secondary education for Zimbabweans, often viewed as a major achievement. But he was slow to embark on land reform that would have taken away the rich farms mostly owned by white farmers. In elections in 1985, he was furious that white voters came out in favor of Mr. Smith. For Mr. Mugabe, the ballot was an affront.

In 1988, Mr. Mugabe became Zimbabwe’s first executive president. But challenges were building and by 2000, when voters registered growing dissatisfaction with him, his earlier benevolence toward white farmers finally evaporated.

Confronted by a clamor for land reform, Mr. Mugabe embarked on an often violent campaign to expropriate white-owned farmland. Soon after, he turned to the task of suppressing a nascent opposition, just as he had suppressed Mr. Nkomo and his followers.

In widely disputed elections in 2008, Mr. Mugabe’s security forces and loyalists beat, killed or intimidated thousands of opposition supporters, prompting their leader, Morgan Tsvangirai, to withdraw from a runoff vote. Mr. Mugabe was declared the winner until international pressure forced him into a power-sharing government with Mr. Tsvangirai.

In 2013, elections were again flawed but Mr. Mugabe emerged triumphant, ending the power-sharing arrangement and insisting that he would run again in 2018 — a prospect that now seems unlikely.

Beyond his borders, his country faced sanctions. He was barred from travel to the West except to attend international gatherings. He sought help from China as it spread its influence across Africa, and he depicted himself as a voice against colonialism — a stance that often undermined any attempts by other African leaders to criticize him in public.

But, at home, he seemed increasingly loyal to the political aspirations of his wife, breaking his ties with those who had been his allies in the liberation war, notably Mr. Mnangagwa. But even before that, Mr. Mugabe had dismissed another former vice president, Joice Mujuru, who seemed to be at daggers drawn with Mrs. Mugabe. She, too, had been a guerrilla fighter, with the nom de guerre “Spill Blood.”

Mr. Mugabe traveled often to Asia for medical treatment that seemed to rejuvenate him, so much so that he once compared himself to the biblical Lazarus, rising from the dead.

Politically, he did not even acknowledge that the end might one day come without divine intervention. In a speech before the African Union in 2016, indeed, he said would remain at the helm “until God says: Come.”