Before starting the script, the screenwriters John Rice and Joe Battelle and the two producers carefully studied all the information about the Navajo and the Marines in the Pacific battlefield. They decided to make the Saipan battle the whole film. Background, and conceive a large number of scenes based on anecdotes in written records.
The film was all shot in Hawaii and Southern California. During the five-month shooting, the first thing to start was the Saipan battlefield where the opening shots flew. The filming location chosen by the crew is a private ranch on Oahu near Honolulu. The ranch covers an area of nearly 4,000 acres and the terrain is very similar to Saipan in the Pacific.
Many of the extras in the film are veterans, reserve soldiers and active soldiers who are on vacation. Before the filming started, most of the leading actors and core extras participated in a week of rigorous military training. With the strong assistance of the Ministry of Defense, they were able to receive basic training at the real Marine Corps base.
