His father, William H. Graham, who died in 1940, met and married his wife Jeanne Marie Augereau while serving in the US military during World War I in St. Nazaire.
At the age of 19, Pierre left France for the United States enrolled in the Merchant Marine Academy in Kingsport, New York; after graduating, he continued to serve in the US Navy from 1943 through 1946 as a lieutenant in the Pacific.
After the war, he married Lorraine Shurman, and received his master's degree from the University of Chicago.
He was nominated as United States Ambassador to Upper Volta by President Nixon in 1974 and remained in that post until he retired in 1978.
Graham left behind his sister and three daughters, Diane Lyn Cooper, Katherine Joan Graham, and Patricia Ann Reed, as well as five grandchildren in the United States, two nephews and their 3 daughters in France.