To his legions of admirers, Mike Hoare was a poetry-reading soldier of fortune who led an army of white mercenaries in Congo, freed missionaries from certain death and beat back a growing communist threat.

He served with the British army in India and Myanmar, also known as Burma, during World War II, worked as an accountant in peacetime London and decamped to apartheid-era South Africa in search of ad­ven­ture. He organized safaris, embarked on motorcycle expeditions that spanned the continent and searched for a legendary lost city in the Kalahari Desert.

Mr. Hoare, who was 100 when he died Feb. 2, eventually found his calling as a mercenary, leading two 1960s campaigns in Congo. Covertly backed by the CIA, he and his men stifled a ragtag rebellion that U.S. policymakers deemed a Cold War menace. But while his soldiers were glamorized by the American press, other reports indicated they were little more than rifle-wielding thugs — guilty of "serious excesses," as one CIA cable put it, that included "robbery, rape, murder and beatings."

Those accusations did little to damage the public image of Mr. Hoare, who sometimes went by the military rank of colonel and said he had little tolerance for war crimes, even as he likened African nationalists to animals. His mercenary career ended two decades later after he spearheaded a failed coup in the Seychelles that landed him in a South African prison.

“I think I’d like to have been born in the time of Sir Francis Drake,” he once told The Washington Post. “Yes, out sailing, robbing the Spaniards, and when you brought the booty back to Queen Elizabeth, you knelt before her and she made you a knight. You were respectable — even though you were a thief.”

Along with Bob Denard of France and Jean Schramme of Belgium, Mr. Hoare was one of several white mercenaries who made international headlines in post-colonial Africa, selling their services to rebel factions and anti-communist regimes. His death was announced by his son and biographer, Chris Hoare, who said Mr. Hoare died at a care facility in Durban, South Africa, but did not give a cause.

“ ‘Mad Mike’ was an officer and a gentleman — with a bit of brigand thrown in,” Chris Hoare said in a statement. Indeed, Mr. Hoare partly inspired a Richard Burton war film, said he shot the toes off a rapist mercenary, and boasted to reporters that he worked only with cleanshaven professionals. In Congo, he had at least one other work requirement as well, once telling an aspiring black gunslinger, “We only engage white mercenaries.”

Mr. Hoare’s commercial soldiering began in 1961, when he traveled to Congo to fight for Moise Tshombe, who sought to establish a breakaway state in the wealthy Katanga province. The revolt failed — Mr. Hoare later said two of his men were cannibalized by enemy forces — but three years later, Tshombe rose to become the country’s prime minister, positioning himself as a staunch American ally and anti-communist crusader.

Tshombe took office amid a growing rebellion led by fighters known as Simbas (the Swahili word for lions), who were reportedly backed by the Soviet and Chinese governments and later joined by Cuban revolutionary Che Guevara. Treating Congo as a Cold War battleground, U.S. authorities encouraged Tshombe to hire mercenaries such as those led by Mr. Hoare, who called communism “the greatest cancer the world has ever known.”

Working alongside Congolese military leader Mobutu Sese Seko, who later ruled the country for three bloody decades, Mr. Hoare assembled a force of several hundred men known as 5 Commando and nicknamed the Wild Geese — a centuries-old term for Irish soldiers and mercenaries, reflecting Mr. Hoare’s own Irish heritage.

“I believe . . . we have a great mission here,” he told a fellow mercenary, according to a history of the Simba rebellion by Johns Hopkins professor Piero Gleijeses. “The Africans have gotten used to the idea that they can do what they like to us whites, that they can trample on us and spit on us.”

Dubbed “the white giants,” Mr. Hoare’s men swept through the country, mowing down untrained and outnumbered Simba forces who believed that witchcraft made them impervious to bullets. In total, the mercenary unit was paid about $300,000 a month by U.S. authorities, according to a Post report, and backed by what the New York Times described as an “instant air force” created by the CIA.

In November 1964, Mr. Hoare’s men closed in on Stanleyville (now Kisangani), a Simba stronghold where about 1,600 missionaries, Europeans and Americans had been taken hostage. Belgian paratroopers rained down on the city and the mercenaries swooped in to provide support. Almost all of the hostages were freed and evacuated by plane.

Mr. Hoare was lionized for his exploits even as accounts of wartime atrocities trickled out of Congo. A Post correspondent recalled that the soldiers were usually orderly, but when Mr. Hoare “wasn’t there, they killed a lot of people and hit the bank.” In an off-the-record conversation with a British journalist, Mr. Hoare called his men “appalling thugs,” according to Gleijeses’s book “Conflicting Missions.”

“Killing communists is like killing vermin; killing African nationalists is as if one is killing an animal,” Mr. Hoare told journalists, according to the Guardian. “My men and I have killed between 5,000 to 10,000 Congo rebels in the 20 months that I have spent in the Congo. But that’s not enough. There are 20 million Congolese you know, and I assume that about half of them at one time or another were rebels whilst I was down here.”

Mr. Hoare took a break from soldiering to embark on a worldwide cruise aboard his 38-foot yacht. He also returned to accounting and, in 1978, attracted wider renown with the release of “The Wild Geese,” a British-Swiss movie that starred Burton as a mercenary loosely modeled after Mr. Hoare, a technical adviser for the film.

Three years later, at age 62, he led more than 40 men in a failed effort to overthrow the socialist government of the Seychelles, an archipelago nation in the Indian Ocean.

Armed with AK-47 assault rifles concealed in false-bottom bags, they posed as rugby players and adopted the name of a drinking club, Ye Ancient Order of Froth-Blowers.

The plan fell apart as the men passed through airport customs on the island of Mahé, where authorities uncovered one man’s rifle, resulting in a firefight that left a mercenary and a Seychelles army officer dead.

Mr. Hoare’s men commandeered an Air India plane and ordered the crew to fly more than 2,000 miles to Durban, South Africa, where the hijackers were subsequently arrested. At trial, Mr. Hoare testified that the South African government had approved the coup and supplied his men with weapons; Prime Minister P.W. Botha later denied having authorized the attack, although a U.N. investigation found that the South African government probably had advance knowledge of the plot.

All but one of the mercenaries were convicted of hijacking, and Mr. Hoare was sentenced to 10 years in prison. He was released less than three years later under a 1985 presidential amnesty and rebuffed questions about his potential retirement. “This is all a question of opportunity,” he told the Associated Press. “Mercenary opportunities exist now mainly in films and books.”

Thomas Michael Bernard Hoare was born in what was then Calcutta, in British colonial India, on March 17, 1919.

His father was an assistant dock master, and Mr. Hoare spent much of his youth in England before serving with the London Irish Rifles and the Royal Armoured Corps during World War II. He mustered out as a major and emigrated to South Africa in 1948.

Mr. Hoare burnished his legacy in a slew of memoirs, and late in life spent two decades in France, studying a medieval Christian sect known as the Cathars that he chronicled in a historical novel. He returned to South Africa in 2009.

His marriage to Elizabeth Stott ended in divorce, and in 1961 he married Phyllis Sims. She died in 2009. Survivors include two sons and a daughter from his first marriage; two sons from his second; two brothers; two sisters; and eight grandchildren.

Mr. Hoare said it was not simply money or ideology that led him to become a mercenary.

“The mystique is unexplainable — the mystique about soldiering with strong men,” he told The Post in 1978. “It’s something more than just soldiering for money. The moment of truth comes at 3 a.m. in a hole. Your buddy’s been killed or wounded, and no money can compensate . . . But there’s an indescribable exhilaration being part of a well-disciplined unit that holds its position.”