The film Glory is based largely on the letters of Robert Gould Shaw, the essay "Lay This Laurel" by Lincoln Kirstein, and the book One Gallant Rush: Robert Gould Shaw and his Brave Black Regiment by Peter Burchard. Screenwriter Kevin Jarre adapted the biographical account of Shaw and the 54th Massachusetts Regiment in a broadly accurate sense to write a fictional story for film. The filmic events within the overall timeline of this man and the all-black volunteer unit are presented in the film fairly and without exaggeration. In order to tell the most important aspects of their story, Jarre's adapted screenplay must narrow Shaw's life and his background to only what is relevant to the 54th. The timeline of the regiment, likewise, is shortened and appropriately ends early with its climactic assault on Fort Wagner. It is this event by which the public audience remembered and remembers their existence.
Director Edward Zwick played a large role in shaping the portrayal of the main characters, having read a variety of sources to rewrite the screenplay. Included in them were Thomas Wentworth Higginson's memoir Black Life in an Army Regiment (1869), oral histories of former slaves, all 1,300 of Shaw's letters, and the consultation of historian Shelby Foote (Cullen 155-56).
In simpler terms, the omissions and modifications of Shaw and the 54th can be excused, for they do not take away from the respective true-life experiences of them both. For the drama that Zwick develops, the fictional characters only serve to highlight the exceptional feats of the regiment and their nothing less than courageous undertakings.