C.T. Vivian, the late civil rights activist and close adviser to Martin Luther King Jr., will be remembered in a private funeral service Thursday in Atlanta.

Vivian was a monumental figure in the Civil Rights Movement, with a stretch of advocating for racial equality for more than six decades from his first sit-in demonstrations in the 1940s in Peoria, Illinois. He met King soon after the 1955 Montgomery bus boycott.  

Vivian died of natural causes July 17 at age 95 at his home in Atlanta. It was the same day that fellow civil rights leader U.S. Rep. John Lewis died.

Here are five things to know about Vivian.

1. Vivian first led a sit-in in 1947

While working in his first professional job as a recreation director for the Carver Community Center in Peoria, Illinois, Vivian led his first-ever sit-in.

The demonstrations aimed to desegregate Peoria's Barton’s Cafeteria and served as a pivotal moment in Vivian's career as an activist, marking the first time he used non-violent, direct-action movement to spur change. It would not be the last time he would do so.

While studying at American Baptist College in Nashville, Vivian teamed with future civil rights leaders Diane Nash, Bernard Lafayette, James Bevel, James Forman and John Lewis – who would go on to become a congressman – for a non-violent march. On April 19, 1960, Vivian was one of around 4,000 demonstrators who marched on City Hall in Nashville and persuaded then-Mayor Ben West to publicly agree that racial discrimination was morally wrong.