Diana sits on her suitcases as she prepares to go to boarding school at Riddlesworth Hall in the fall of 1970. Distraught over the separation from her home, she told her father, “If you love me, you won’t leave me here.” PHOTOGRAPH BY (SPEN/AL), CAMERA PRESS, REDUX

Diana grew up surrounded by dogs, cats, hamsters, rabbits, and horses. “She loved animals when she was a child,” her mother said. “She loved everything that was small and furry or had feathers. ”Diana learned to ride horses before she was four, but after she broke her arm in a riding accident, her love faded. Still, her empathy for all living creatures would be a hallmark of her life. Here she holds her pet guinea pig during a 1972 pet show in Sandringham. She brought her guinea pig to her first boarding school, Riddlesworth Hall, where she was made head of “Pets’ Corner,” where the students’ pets were housed. PHOTOGRAPH BY (SPEN/AL), CAMERA PRESS, REDUX

As her star grew, Diana’s admirers became taken with the princess’s eye for fashion, as well as her charm. Here, she dresses in plaid at the Braemar Highland Games in Scotland. September 1982 PHOTOGRAPH BY ANWAR HUSSEIN, GETTY IMAGES

Days before their wedding, Prince Charles and Lady Di pose together. July 1981 PHOTOGRAPH BY KEYSTONE-FRANCE, GETTY IMAGES

A royal wedding portrait in the Throne Room at Buckingham Palace. The former Lady Diana Spencer, now the Princess of Wales, stands at center with her prince. The Queen (wearing a blue dress) stands next to the Queen Mother (in a teal dress) on the left. Diana’s mother, Frances (in green), is next to her father, Earl Spencer, on the right. The wedding brought together two families and ended the speculation over the bachelorhood of Prince Charles. PHOTOGRAPH BY LICHFIELD, GETTY IMAGES

To promote her message on behalf of the charity HALO Trust, Diana walked through an active minefield in Huambo, Angola, in front of the press. The cause was more important than the inherent danger she faced. January 15, 1997 PHOTOGRAPH BY TIM GRAHAM, GETTY

Lady Diana Spencer was only 20 years old when she married Prince Charles and became the United Kingdom’s own Princess of Wales. To the 750 million viewers who watched her 1981 wedding on television, Diana was a charming, down-to-earth princess who’d won her fairy tale marriage. But a decade later she sadly described the wedding as “the worst day of my life.”

Princess Di, as she was affectionately known, made that confession during a series of taped interviews with journalist Andrew Morton, who was writing a book about her life. She spoke candidly about her troubled marriage, her struggle with bulimia, and her difficulty handling life in the public eye. Most of the material has never been broadcast, but on Monday, August 14 at 9/8c, the tapes will resurface in Diana: In Her Own Words, a documentary premiering on National Geographic.