From a blog (Crooked Timber) I follow, this story:
In 1985, Franklin was in New York to receive the Clarence Holte Literary Award for his biography of historian George Washington Williams, a 40-year project for which he was a runner-up for the Pulitzer Prize. The next morning, he and his wife were unable to hail a taxi in front of their hotel. Ten years later, when he was to receive the [Presidential Medal of Freedom], Franklin hosted a party for some friends at Washington’s Cosmos Club, of which he had long been a member. A white woman walked up to him, handed him a slip of paper and demanded that he get her coat. He politely told the woman that any of the uniformed attendants, “and they were all in uniform,” would be happy to assist her.
Duke’s Tribute to John Hope Franklin
Born and raised in an all-black community in Oklahoma where he was often subjected to humiliating incidents of racism, he was later instrumental in bringing down the legal and historical validations of such a world.
As an author, his book ''From Slavery to Freedom'' was a landmark integration of black history into American history. As a scholar, his research helped Thurgood Marshall win Brown v. Board of Education, the 1954 case that outlawed the doctrine of ''separate but equal'' in the nation's public schools.
HWPL's record on the original book:
From slavery to freedom: a history of Negro Americans. New York, Knopf 
From slavery to freedom: a history of African Americans. John Hope Franklin, Alfred A. Moss, Jr. New York: McGraw-Hill, 1994
From slavery to freedom: a history of African Americans. John Hope Franklin, Alfred A. Moss, Jr. Boston: McGraw-Hill, c2000.
Above all, he documented how blacks had lived and served alongside whites from the nation's birth. Black patriots fought at Lexington and Concord, Franklin pointed out in ''From Slavery to Freedom,'' published in 1947. They crossed the Delaware with Washington and explored with Lewis and Clark. The text sold million of copies and remains required reading in college classrooms.