Cornelius Ryan (5 June 1920 – 23 November 1974) was an Irish journalist and author known mainly for writing popular military history.

He was especially known for his histories of World War II events: The Longest Day: 6 June 1944 D-Day (1959), The Last Battle (1966), and A Bridge Too Far (1974).

He was an altar boy at St Kevin's Church, Harrington Street and studied the violin at the Irish Academy of Music in Dublin.

After the US entered the war, he flew along on fourteen bombing missions with the Eighth and Ninth United States Army Air Forces (USAAF).

[3] On a trip to Normandy in 1949, Ryan became interested in telling a more complete story of Operation Overlord than had been produced to date.

He began compiling information and conducting over 1000 interviews as he gathered stories from both the Allies and the Germans, as well as French civilians.

[5] After publishing an article about the ditching for Collier's in their 21 December 1956, issue, Ryan expanded it and developed it as a book.

It deals with the fraught military and political situation in mid-1945, when the western Allies and the Soviet Union competed to liberate Berlin and occupy Germany.

[7][8][9] Ryan followed this work by A Bridge Too Far (1974), which tells the story of Operation Market Garden, the ill-fated assault by Allied airborne forces on the Netherlands, culminating in the Battle of Arnhem.