John Leo Flannery was born in Archbald, Pennsylvania, on July 6, 1904. He received his early education from Archbald public schools and St. Thomas High School, and College (now Scranton University). He then attended Georgetown University in Washington, DC, from which he received the degrees of Bachelor of Science in 1927, and Doctor of Medicine in 1929. After a period of internship, he practiced General Medicine in Archbald for five years and Pediatrics in Harrisburg for six years thereafter.
He entered active service in the US Naval Reserve on April 27, 1942, having been commissioned as a Lieutenant Commander in the Medical Corps on March 17, 1942. He was promoted to Commander effective November 18, 1942 and after his transfer to the US Navy in July 1947, was advanced to the rank of Captain, his date of the rank January 1, 1951.
Reporting to the Naval Hospital, Chelsea, Massachusetts, in April 1942, shortly after the United States entered World War II, he remained there for a brief period of indoctrination, after which he served from June 16, 1942 to April 8, 1943 at Naval Supply Corps School and the Naval Training School, both units of Harvard University, located in Boston and Cambridge, Massachusetts, respectively. On April 13, 1943 he reported for duty first with the US Marine Training School, Fleet Marine Forces, Camp Lejeune North Carolina, and with the Medical Battalion there from May 1943 until June 1944.
From July to September 1944 he had duty with Cub 17, Lido Beach, Long Island, New York, and from there he went to Saipan, Marianas Islands, for duty the last year of the war as Senior Medical Officer of the Naval Base # 3245. He returned to the United States in November 1945, and three months later was relived of all active duty on February 19, 1946.
Recalled to active military service on March 3, 1947, he served until October 1948 at Headquarters, Fourth Naval District, Philadelphia, Pennsylvania, with duty in connection with the Naval Reserve Program. He next reported to the University Of Pennsylvania Graduate School Of Medicine, Philadelphia, Pennsylvania, for the course in Pediatrics, and graduating on June 6, 1949 was assigned as Chief, Pediatric Service at the Naval Hospital, Portsmouth, Virginia, until August 10, 1953. Since August 26, 1953, he has been stationed at the Naval Hospital, St. Albans, New York, where he is Chief, Dependents Service.
Captain Flannery has the American Campaign Medal; the Asiatic-Pacific Campaign Medal; the World War II Victory Medal; and the National Defense Service Medal.