Vincent Harding, an aide to the Rev. Martin Luther King Jr., died May 19 at 83. (AP)

Vincent Harding, a historian who was an influential behind-the-scenes figure during the civil rights movement and who wrote a controversial speech for Martin Luther King Jr. that condemned the war in Vietnam, died May 19 in Philadelphia. He was 82.

His death, from an aneurysm, was announced by the Iliff School of Theology in Denver, where he had been a faculty member for more than 30 years. He was on an East Coast speaking tour.

Dr. Harding, who said his service in the Army made him a dedicated pacifist, was a lay minister in Chicago when he began working for the civil rights movement in the late 1950s. He moved to Atlanta in 1961, settling around the corner from King’s family.

Soon afterward, Dr. Harding and his wife founded the Mennonite House, one of the South’s first interracial gathering places for proponents of civil rights.

While teaching at Atlanta’s Spelman College in the mid-1960s, Dr. Harding began to explore the moral implications of U.S. involvement in Vietnam. He wrote a letter to King and other civil rights leaders outlining a critical stance toward the war, then composed a speech for King that addressed Vietnam in the context of civil rights.

King delivered the speech at New York’s Riverside Church on April 4, 1967 — one year to the day before he was assassinated in Memphis. The speech, often called “A Time to Break Silence,” was little changed from Dr. Harding’s original draft.

“A time comes when silence is betrayal,” King said. “And that time has come for us in Vietnam.”

He called the U.S. government “the greatest purveyor of violence in the world today” and said it was morally indefensible to send African American troops to “guarantee liberties in Southeast Asia which they had not found in southwest Georgia and East Harlem.”

King concluded that “a nation that continues year after year to spend more money on military defense than on programs of social uplift is approaching spiritual death.”

An overflow crowd of 3,000 gave King a standing ovation, but his message was not well received in other circles. A New York Times editorial criticized King’s views, and the NAACP called the speech a “serious tactical error.”

Sen. Barry Goldwater (Ariz.), who was the Republican presidential nominee in 1964, said the speech “could border a bit on treason.”

Neither King nor Dr. Harding ever recanted the speech, which was seen as bringing together the two major tides of protest in the 1960s: civil rights and the antiwar movement.

In his later academic work as a historian, Dr. Harding wrote several books describing the development of radical ideals among African Americans and said King belonged squarely in that tradition.

The 1967 speech condemning the Vietnam War, Dr. Harding said, was not an anomaly but was a pure reflection of King’s evolving views of the role of civil rights on the world stage.

“For those who seek a gentle, nonabrasive hero whose recorded speeches can be used as inspirational resources for rocking our memories to sleep,” Dr. Harding told the National Catholic Reporter in 1997, “Martin Luther King Jr. is surely the wrong man.”

Vincent Gordon Harding was born July 25, 1931, in New York City and was raised by a single mother who worked as a cleaning woman.

He graduated from City College of New York in 1952 and received a master’s degree in journalism from Columbia University in 1953 before serving in the Army for two years. He received a master’s degree in 1956 and a doctorate in 1965, both in history from the University of Chicago.

A Seventh-day Adventist early in life, Dr. Harding later adopted the Mennonite faith, known for its pacifist beliefs.

After King’s death, Dr. Harding became the first director of what was then the Martin Luther King Jr. Memorial Center and then led the Institute of the Black World, both in Atlanta. In 1974, Dr. Harding moved to Philadelphia to teach at Temple University and later the University of Pennsylvania. He joined the faculty of Denver’s Iliff School of Theology in 1981.

He wrote or edited more than 20 books, including “The Other American Revolution” (1980), “There Is a River: The Black Struggle for Freedom in America” (1981) and “Martin Luther King: The Inconvenient Hero” (1996).

In the 1970s and 1980s, Dr. Harding was a prominent voice in an often-heated debate over the purpose and direction of black studies courses. Although he had been educated at mixed-race or predominantly white institutions from high school through graduate school, Dr. Harding advocated a form of racial separatism in education, at least for a while.

“Those who have colonized us for 300 years are essentially unqualified to educate our children,” he wrote in the Times in 1970.

Dr. Harding believed African American communities should develop “alternatives to white public and private education” and “the means to keep these black experiments in educational creativity under the control of the black community.”

Other scholars, both black and white, criticized his views as polarizing and academically unsound.

It would be “a very serious error,” Michael R. Winston, director of Howard University’s Moorland-Spingarn Research Center, told The Washington Post in 1982, to believe “there’s no room for conventional scholarship in black studies.”

After moving to Denver, Dr. Harding helped establish the Veterans of Hope Project, a multidisciplinary effort combining historical, religious and cultural studies with political action. His first wife, Rosemarie Freeney Harding, who died in 2004 after 43 years of marriage, helped run the project.

With his second wife, Aljosie Aldrich Harding, whom he married in December 2013, Dr. Harding helped launch the National Council of Elders, a mentoring group to train young social activists. He was also a consultant to the multi-episode civil rights documentary “Eyes on the Prize,” which premiered on PBS in 1987.

In addition to his wife, survivors include two children from his first marriage.

On the 45th anniversary of King’s assassination, Dr. Harding reflected on the changes that he had seen in the years since the powerful speech he had written about Vietnam.

“It’s clear that we have not learned from the experience of the 30-40 years since Vietnam,” he told the Macon Telegraph in Georgia in 2013. “We’ve been in wars almost continuously since then. . . .

“If we look with sobriety, the real message is war begets war. Every war becomes an excuse for another war.”