Gene Sharp at his office in Boston in 2009. (Elise Amendola/ASSOCIATED PRESS)

Gene Sharp, a scholar and onetime conscientious objector who wrote penetratingly about civil disobedience, was often called "the Machiavelli of nonviolence" and who became an influential backstage figure in international peace movements from Serbia to Egypt, died Jan. 28 at his home in Boston. He was 90.

The death was confirmed by Jamila Raqib, executive director of the Albert Einstein Institution, a Boston-based nonprofit organization Dr. Sharp founded in 1983 to advance "the study and use of strategic nonviolent action in conflicts throughout the world." The cause of Dr. Sharp's death was not disclosed.

From his academic perches at Harvard and elsewhere and his prolific writing about the peace movement's dynamics, theories and strategies, Dr. Sharp helped provide the intellectual energy accessed by activists confronting dictators and strongmen around the world. His books, including the three-volume "The Politics of Nonviolent Action" (1973), were translated into dozens of languages.

Dr. Sharp, who was inspired by Mohandas K. Gandhi, the Rev. Martin Luther King Jr. and other proponents of civil disobedience, saw himself as a pragmatist who advised specific actions such as "sick-ins," mockery of authoritarian rulers and declining to use officially sanctioned currency. He disliked being called a pacifist or a "peace researcher," telling Progressive magazine such descriptions were "quite naive" and that conflict was often preordained and necessary.

That did not mean engaging in conventional warfare and other violent tactics. "Why should you choose to fight with your enemy's best weapons?" he told National Public Radio. "That doesn't make sense at all. Nonviolent struggle is a kind of people-power. You have a much greater chance of succeeding by you choosing the means that they're not equipped to deal with effectively."

He wrote of nonviolence as an "alternative weapons system" and described it a "means of combat, as in war. It involves the matching of forces and the waging of 'battles,' it requires wise strategy and tactics, employs numerous 'weapons' and demands of its 'soldiers' courage, discipline and sacrifice."


Gene Sharp in 2009. (Elise Amendola/ASSOCIATED PRESS)

Among those taking to heart his teachings were Yugoslav students in 1998 and their Serbian group Otpor (Resistance). With no tanks, bombs or guns, but well armed with 5,000 copies of Dr. Sharp's 1993 volume "From Dictatorship to Democracy," they found moral support and a road map for their cause.

Slobodan Milosevic, the "Butcher of the Balkans," had managed to cling to power despite NATO bombing of Serbia and other efforts to dislodge him. Violent attacks by outside forces only empowered Milosevic's repressive leadership and justified a crackdown on opposition movements. It was only after Milosevic tried to stay in power after he lost an election in September 2000 that Otpor saw its moment — with displays of civil disobedience and mockery that were credited with helping topple him.

Milosevic was removed from office that October and the following April was arrested on charges of genocide and war crimes. He died before a verdict was reached. In two years of organized resistance, no Otpor member was killed.

Some peace activists saw the hand of Dr. Sharp's writings in uprisings from Burma to Ukraine and resistance struggles from Latin America to Africa. Regimes in Syria, Iran and Venezuela have reportedly accused him of being on the payroll of the CIA and the White House. (He denied any connection to any governments.)

His books were said to have had an impact on leaders of the 2011 Arab Spring protests in Cairo's Tahrir Square against Egyptian president Hosni Mubarak. Dr. Sharp said perhaps the most important lesson embraced by the young activists, whose persistence led to Mubarak's resignation, was loss of fear.

"Once a regime is no longer able to frighten people," he told NPR, "and people then act wisely and keep nonviolent discipline, which is extremely important, then that regime is in big trouble."

Gene Elmer Sharp was born Jan. 21, 1928, in North Baltimore, Ohio, and spent his high school years in Columbus. His father was a traveling Protestant minister, his mother a teacher. He was a 1949 graduate of Ohio State University, where he also received a master's degree in sociology in 1951.

He moved to New York and worked as an elevator operator and a guide for a blind social worker. "I wasn't interested in having a real job," he told the New York Times in 2012. "I wanted subway fare and food and to research Gandhi."

He protested his conscription for military service during the Korean War. Arrested and convicted as a conscientious objector, he served more than nine months in the Danbury, Conn., federal prison. He passed the time reading.

Aware that physicist Albert Einstein was a pacifist, Dr. Sharp wrote to him at Princeton University for his views on conscientious objection. The scientist wrote to the 25-year-old dissident: "I earnestly admire you for your moral strength and can only hope although I really do not know that I would have acted as you did had I found myself in the same situation."

Uplifted by the reply, Dr. Sharp, then working on his book "Gandhi Wields the Weapon of Moral Power," persuaded Einstein to write the foreword. It came out in 1960, five years after Einstein's death. In the intervening years, Dr. Sharp worked in the United States for pacifist A.J. Muste and spent a period in Norway, studying the country's nonviolent resistance movement against a pro-fascist regime during World War II. Some citizens, he noted, put a potato or toothpick on their clothes as a silent protest.

"Everyone always talks about the boys in the mountains fighting against the Nazis," he told the Times, "but what interested me was the teachers, the clergy and the labor movement. Those were the real resisters."

Dr. Sharp received a doctorate in political theory from the University of Oxford in 1968. He taught political science and sociology at the University of Massachusetts at Dartmouth, among other colleges.

Among his honors was the 2012 Right Livelihood Award, sometimes called the Alternative Nobel. He was the subject of Ruaridh Arrow's 2011 documentary "How to Start a Revolution."

Dr. Sharp never married. Survivors include a brother.

"In a world that often considers the use of force as the only 'realistic' option when confronted with crises and threat, Gene Sharp dedicated his life's work to show us another way," said Randall Amster, director of the Justice and Peace Studies Program at Georgetown University. "We have lost a great peacemaker."

Colman McCarthy, a former Washington Post columnist, directs the Center for Teaching Peace in Washington.