The retelling of June 6, 1944, from the perspectives of the Germans, US, British, Canadians, and the Free French. Marshall Erwin Rommel, touring the defenses being established as part of the Reich's Atlantic Wall, notes to his officers that when the Allied invasion comes they must be stopped on the beach. "For the Allies as well as the Germans, it will be the longest day"
| Writing | Cornelius Ryan | Screenplay |
| Production | Darryl F. Zanuck | Producer |
| Camera | Jean Bourgoin | Director of Photography |
| Directing | Andrew Marton | Director |
| Directing | Bernhard Wicki | Director |
| Sound | Maurice Jarre | Original Music Composer |
| Camera | Walter Wottitz | Director of Photography |
| Directing | Ken Annakin | Director |
| Writing | Cornelius Ryan | Novel |
| Editing | Samuel E. Beetley | Editor |
| Production | Maude Spector | Casting |
| Art | Léon Barsacq | Art Direction |
| Crew | Johnny Borgese | Special Effects |
| Art | Vincent Korda | Art Direction |
| Production | Elmo Williams | Associate Producer |
| Art | Ted Haworth | Art Direction |
| Art | Gabriel Béchir | Set Designer |
| Writing | Jack Seddon | Writer |
| Writing | David Pursall | Writer |
| Writing | James Jones | Writer |
| Writing | Romain Gary | Writer |
| Sound | Joseph de Bretagne | Sound |
| Crew | Lucie Maria Rommel | Technical Advisor |
| Crew | Roger Bligh | Technical Advisor |
| Sound | William Robert Sivel | Sound |
| Crew | Fernand Prevost | Technical Advisor |
| Crew | E. C. Peake | Technical Advisor |
| Crew | Max Pemsel | Technical Advisor |
| Crew | Günther Blumentritt | Technical Advisor |
| Crew | The Earl of Lovat | Technical Advisor |
| Crew | Joseph B. Seay | Technical Advisor |
| Crew | John Howard | Technical Advisor |
| Crew | A. J. Hillebrand | Technical Advisor |
| Crew | Albert Saby | Technical Advisor |
| Directing | Tom Pevsner | Assistant Director |
| Crew | Frederick Morgan | Technical Advisor |
| Sound | Mitch Miller | Music Arranger |
| Crew | James Gavin | Technical Advisor |
| Crew | Philippe Kieffer | Technical Advisor |
| Crew | Josef Priller | Technical Advisor |
| Crew | Friedrich Ruge | Technical Advisor |
| Directing | Bernard Farrel | Assistant Director |
| Crew | Pierre Koenig | Technical Advisor |
| Crew | James R. Johnson | Technical Advisor |
| Directing | Gérard Renateau | Assistant Director |
| Crew | Willard L. Bushy | Technical Advisor |
| Crew | Helmuth Lang | Technical Advisor |
| Crew | Hubert Deschard | Technical Advisor |
| Crew | Werner Pluskat | Technical Advisor |
| Crew | Jean Barral | Technical Advisor |
| Crew | Paul Anka | Additional Music |
| Directing | Louis Pitzele | Assistant Director |
| Sound | Jacques Maumont | Sound |
| Crew | Jean Fouchet | Special Effects |
| Directing | Gerd Oswald | Director |
| Directing | Darryl F. Zanuck | Director |
| Directing | Henry Wise | Second Assistant Director |
| Directing | Jean Herman | Assistant Director |
| Directing | Gerd Oswald | Second Unit Director |
| Directing | Henry Sokal Jr. | Assistant Director |
| Directing | Elmo Williams | Second Unit Director |
| Crew | Karl Baumgartner | Special Effects |
| Crew | Joseph de Bretagne | Special Effects |
| Crew | Gerald Endler | Special Effects |
| Crew | Karl Helmer | Special Effects |
| Crew | Augie Lohman | Special Effects |
| Crew | R.A. MacDonald | Special Effects |
| Crew | Fernando Pérez | Special Effects |
| Crew | Alex Weldon | Special Effects |
| Crew | Paul Wurtzel | Special Effects |
| Visual Effects | Wally Veevers | Visual Effects |
| Crew | Ken Buckle | Stunts |
| Crew | Yvan Chiffre | Stunts |
| Crew | Jack Cooper | Stunts |
| Crew | Gil Delamare | Stunts |
| Crew | Jean-Pierre Janic | Stunts |
| Crew | Gérard Moisan | Stunts |
| Crew | Joe Powell | Stunts |
| Crew | Nosher Powell | Stunts |
| Crew | Alexandre Renaud | Stunts |
| Crew | John Sullivan | Stunts |
| Crew | Lionel Vitrant | Stunts |
| Crew | Ian Yule | Stunts |
