Kathleen Cavendish

Kathleen Agnes Cavendish, Marchioness of Hartington (née Kennedy), was born on February 20, 1920, in Brookline, Massachusetts. She was the second daughter and fourth child of Joseph P. Kennedy Sr. and Rose Fitzgerald. Her siblings included John F. Kennedy, who later became the 35th President of the United States; Robert F. Kennedy, a U.S. Senator; Ted Kennedy, also a U.S. Senator; Rosemary Kennedy; Eunice Kennedy; Patricia Kennedy; Jean Kennedy; and Joseph Kennedy Jr.

Kennedy was nicknamed "Kick" due to her "irrepressible nature." She received education at Riverdale Country School in the Bronx, New York City; Noroton Convent of the Sacred Heart in Noroton, Connecticut; and Holy Child Convent in Neuilly, France. During her childhood, she was active in sports, notably playing football with her brothers, influenced by her father's emphasis on competition. The Kennedy children benefited from substantial educational and social opportunities, particularly after Joseph P. Kennedy was appointed U.S. ambassador to the United Kingdom in 1938.

While in Britain, Kennedy became involved in social life and was introduced into high society. She attended Queen’s College in London and was declared the "debutante of 1938" at the Queen Charlotte’s Ball. During this period, she cultivated friendships among British aristocracy and socialites, including dating David Rockefeller. Her time in England coincided with the onset of World War II; following the German invasion of Poland in September 1939, Kennedy was in the south of France and traveled to England with her friend Janey Kenyon Slaney. The Kennedy family returned to the United States for safety, but Kennedy expressed a desire to remain in London, which was ultimately overridden by her parents.

After returning to the U.S., Kennedy enrolled at the Finch School and Florida Commercial College. She volunteered with the American Red Cross and in 1941 began working as a research assistant for Frank Waldrop of the Washington Times-Herald. She later collaborated with Inga Arvad on a column reviewing films and plays.

In 1943, Kennedy sought to return to England and volunteered with a Red Cross servicemen’s center. During this period, she developed a romantic relationship with William Cavendish, Marquess of Hartington, the heir apparent to the 10th Duke of Devonshire. She had met Hartington in England prior and rekindled their relationship after her return. Her mother, Rose Kennedy, disapproved of their relationship due to religious considerations, as it involved marriage between a Roman Catholic and an Anglican, which would impact the religious upbringing of their children. Despite this opposition, Kathleen married Lord Hartington on May 6, 1944, in a civil ceremony at Caxton Hall Register Office. Only her brother Joseph P. Kennedy Jr. attended the wedding; her other brothers, John F. Kennedy and Robert F. Kennedy, were unable to attend due to military service.

Her husband, Lord Hartington, was killed by a sniper during active service in Belgium four months after their marriage, on August 12, 1944. Her brother Joseph P. Kennedy Jr., an officer in the U.S. Navy, had been killed earlier that year during a bombing mission over the English Channel.

Following her husband's death, Kennedy was styled as the Dowager Marchioness of Hartington. She remained active in London society and was known for her wit and vivacity. She eventually developed a romantic relationship with the 8th Earl Fitzwilliam, who was in the process of divorcing his wife. Her mother again disapproved of this relationship and warned Kennedy of potential disownment and loss of financial support.

On May 13, 1948, Kathleen Kennedy died in a plane crash while flying from Paris to the French Riviera with Lord Fitzwilliam. The aircraft encountered turbulence during the flight, which resulted in structural failure of the plane, causing it to crash near Saint-Bauzile, Ardèche, France. All four occupants—Lady Hartington, Lord Fitzwilliam, the pilot Peter Townshend, and the navigator Arthur Freeman—were killed instantly. She was buried at St. Peter’s Churchyard in Edensor, Derbyshire, England. Her father was the only family member present at her funeral; Rose Kennedy did not attend, citing medical reasons, and her brother John was too distressed to go.

Her life has been depicted in the novel "The Kennedy Debutante," published by Berkley Books in 2018, authored by Kerri Maher.