Personal life Clifford Harmon married Zephyr Hord on September 18, 1887, in Dayton, Ohio; they divorced sometime after 1898. Harmon was later engaged to be married to Blanche Freeman, but broke the engagement in April 1904 to marry Louise Adele Benedict, daughter of Commodore Elias Cornelius (E.C.) Benedict. Freeman sued Harmon for breach of promise in 1909 (after initially suing for $100,000 and withdrawing the suit at Harmon's request), receiving an award of $15,000 in 1910. The award was set aside on appeal and the case retried later.

Harmon left Louise Benedict in 1916 after an argument with E.C. Benedict over support for his daughter. In 1917 Harmon traveled to China, India, and Japan.

On April 22, 1918, Harmon enlisted in the NY Guard Service, Troop A, Squadron A; he was discharged June 12, 1918. On October 13, 1918, he was commissioned as a captain in Air Signal Corps and served in France from November 1918 to January 1919, training aviators. He was discharged from the service January 24, 1919, with the rank of captain and 5% disability.

Harmon was excluded from E.C. Benedict's will when Benedict passed in 1920; Louise Benedict and Clifford Harmon were divorced April 7, 1925.

Harmon moved to Paris, France sometime after 1920 and became involved with Parisian society. He met Madeline Keltie, an opera singer 24 years his junior, in 1924 at the American embassy in Rome, Italy. In May 1925 Harmon was involved in a fistfight in Monte Carlo with Arthur St. John over St. Johns unwanted advances towards Keltie. Keltie and Harmon were engaged to be married in July 1925; the marriage was postponed in November 1925 and the engagement was broken in early 1927. Later in 1927, Clifford Harmon was best man at the marriage of Pola Negri and David M'divani in Paris.