Legendary civil rights activist Julian Bond, one of the original leaders of the Student Nonviolent Coordinating Committee, a former chairman of the NAACP, and a vocal critic of the Vietnam War, died Saturday night after a brief illness. He was 75.

Bond graduated from Morehouse College in Atlanta in 1971 and helped found the Southern Poverty Law Center (SPLC), serving as the organization’s president from 1971 to 1979.

“With Julian’s passing, the country has lost one of its most passionate and eloquent voices for the cause of justice,” SPLC co-founder Morris Dees said in a statement. “He advocated not just for African Americans, but for every group, indeed every person subject to oppression and discrimination, because he recognized the common humanity in us all.”

The Nashville, Tennessee native was one of eight African-Americans elected to the Georgia House of Representatives following the passage of the Civil Rights Act in 1965. White members of the House refused to seat him because of his opposition to the Vietnam War. In 1966, the United States Supreme Court ruled that the House had denied Bond his freedom of speech and had to seat him.

The New York Times reports: “On the strength of his personality and quick intellect, he moved to the center of the civil rights action in Atlanta, the unofficial capital of the movement, at the height of the struggle for racial equality in the early 1960s.”

In a statement, Atlanta Mayor Kasim Reed praised Bond’s “life of great impact, great courage and great distinction.”

“The City of Atlanta is in mourning today,” Reed said. “We have lost one of our heroes.”

Bond served as distinguished adjunct professor in the School of Public Affairs at American University from the 1990s to 2015, incorporating into his classes his personal experiences from being a student of Martin Luther King, Jr. and explaining how the civil rights movement served as a model for subsequent movements including the struggle for gay rights.