Activist and author Susan Sontag died of leukemia on Dec. 28, 2004, at the age of 71. It was Sontag’s third bout with cancer since 1976, a disease that informed much of her writing in the last few decades.

Sontag was born Susan Rosenblatt in New York City, in 1933. Following the death of her father when she was five, the family lived in Arizona and Los Angeles, where her mother married an Army officer, Capt. Nathan Sontag.

After graduating from North Hollywood High School at 15, she attended UC Berkeleyand the University of Chicago. At 17, she married sociologist Philip Rieff. Upon the dissolution of the marriage, less than 10 years later, she moved to New York City and taught courses in the philosophy of religion at Columbia University.

Sontag first gained fame in 1964 with her essay, “Notes on Camp.” Her 17 books include novels, critical essays, short stories and portraits of intellectuals.

She was strongly interested in the arts, feeling that art was a conduit through which humans could examine themselves and the world around them. In addition to “On Photography,” which received a National Book Critics Circle Award in 1978, Sontag contributed an essay to “Women,” the 1999 collection of portraits by photographer Annie Leibovitz. She also wrote and directed two full-length feature films, “Duet for Cannibals” and “Brother Carl.”

Sontag also was active politically, particularly on a global scale, and her travels to Cuba, China, Vietnam and Bosnia occurred when United States was at the height of conflict with those countries.

While serving as president of the American chapter of PEN, the international writers organization, from 1987 to 1989, she spearheaded the organization’s support of Salman Rushdie. She also took a stance against U.S. military involvement in Iraq, a position that earned her much criticism.

She is survived by her son, David Rieff (author of “Going to Miami: Tourists, Exiles and Refugees in the New America” and “The Exile: Cuba in the Heart of Miami”), and sister, Judith Cohen.