Aan het begin van de onafhankelijksheidoorlog tegen Groot-Brittannië hebben de kolonisten Gilbert Martin en Lana Martin te maken met aanvallen van oorlogszuchtige indianen, die door de Britten worden gestuurd. Nadat hun huis met de grond gelijk is gemaakt sluit Gilbert zich aan bij een regiment dat het fort, waar de bevolking uit de vallei naartoe is gevlucht, verdedigt tegen de aanvallen van de indianen.
Nee, helaas is Onder één vlag nog niet beschikbaar op Netflix in Nederland.
| Camera | Bert Glennon | Director of Photography |
| Directing | John Ford | Director |
| Writing | Sonya Levien | Screenplay |
| Production | Darryl F. Zanuck | Producer |
| Sound | Alfred Newman | Original Music Composer |
| Editing | Robert L. Simpson | Editor |
| Writing | Walter D. Edmonds | Novel |
| Camera | Ray Rennahan | Director of Photography |
| Art | Richard Day | Art Direction |
| Writing | Lamar Trotti | Screenplay |
| Art | Mark-Lee Kirk | Art Direction |
| Production | Lew Schreiber | Casting |
| Crew | Jackie Hamblin | Stunt Double |
| Crew | Howard Hill | Stunts |
| Costume & Make-Up | Marie Brasselle | Hairstylist |
| Costume & Make-Up | Robert Cowan | Makeup Artist |
| Costume & Make-Up | Norbert A. Myles | Makeup Artist |
| Costume & Make-Up | Irene Beshon | Hairstylist |
| Costume & Make-Up | Steve Drumm | Makeup Artist |
| Sound | Harold A. Root | Assistant Sound Editor |
| Costume & Make-Up | Ann Barr | Hairstylist |
| Directing | F.E. Johnson | Assistant Director |
| Costume & Make-Up | Myrtle Ford | Hairstylist |
| Directing | Edward O'Fearna | Assistant Director |
| Sound | Robert Parrish | Sound Effects Editor |
| Costume & Make-Up | Newton House | Makeup Artist |
| Directing | Wingate Smith | Assistant Director |
| Art | Thomas Little | Set Decoration |
| Sound | E. Clayton Ward | Sound |
| Sound | Roger Heman Sr. | Sound |
| Production | Raymond Griffith | Associate Producer |
| Visual Effects | Henri Jaffa | Color Designer |
| Visual Effects | Natalie Kalmus | Color Designer |
| Costume & Make-Up | Gwen Wakeling | Costume Designer |