Cornelius Ryan was an acclaimed Irish journalist and author, best known for his popular military history books. He was particularly renowned for his works on World War II events, including The Longest Day: 6 June 1944 D-Day (1959), The Last Battle (1966), and A Bridge Too Far (1974).

Born and raised in Dublin, Ireland, Ryan began his journalism career in London in 1940. During World War II, he worked as a war correspondent for The Daily Telegraph, covering the air war in Europe. He flew on fourteen bombing missions with the Eighth and Ninth United States Army Air Forces and joined General Patton's Third Army, covering its actions until the end of the European war. Ryan then moved to the Pacific theater in 1945 and Jerusalem in 1946.

In 1947, Ryan emigrated to the United States to work for Time magazine, reporting on postwar tests of atomic weapons in the Pacific. He became a naturalized U.S. citizen in 1951 and continued to reside there for the rest of his life.