The film is a drama set in World War II, following a group of United States Marines from boot camp to combat as members of the Communications Platoon, 6th Marines, 2d Marine Division. It depicts the forming of comradeships and the relentless training that the battalion, led by Major "High Pockets" Huxley (Van Heflin), has to undergo. In the battles of Guadalcanal and Tarawa, the battalion is employed only for mop-up duties, but after an out-of-line argument between Huxley and the commanding general (Raymond Massey), they are used as lead battalion in the Battle of Saipan.
Besides describing the battalion's everyday activities, the movie also details the private lives of some of the Marines. On military "R and R" in New Zealand, Andy Hookens (Aldo Ray) falls in love with Pat Rogers (Nancy Olson), the widow of a New Zealand soldier killed at El Alamein; while, during training, Danny Forrester (Tab Hunter) is torn between his sweetheart Kathy (Mona Freeman) and his affair with an older woman, USO manager Mrs. Yarborough (Dorothy Malone).
This film features examples of:
- Betty and Veronica: Danny Forrester is torn between the sweet Girl Next Door Kathy (Betty) and Mrs. Yarborough, the experienced older woman (Veronica).
- Badass Bookworm: Marion is clearly the bookworm of the military group.
- The Glasses Come Off: The bookworm Marion takes his glasses off after being pushed too far by the trouble-making Spanish Joe, and drops Joe with a single punch as Joe attempts to sucker punch him.
- Likes Older Women: Danny Forrester has an affair with Mrs. Yarborough, the USO manager, who's older than him. He realises there is no future in the relationship, however, and breaks it off, and marries his sweetheart Kathy.
- Nerd Glasses: Marion has them, as befitting his position as the bookworm of the group.
- One-Hit Kill: Marion K.O.'s Spanish Joe with a single punch after Joe pushes him one too many times.
- Right Behind Me: Pvt. L.Q. Jones has a habit of launching into unflattering impersonations of the Drill Sergeant Nasty just as said sergeant enters the room behind him.
- Semper Fi
- Southern-Fried Private: Pvt. L.Q. Jones from Alabama. Full of folksy sayings and with the habit of launching into unflattering impersonations of the Drill Sergeant Nasty just as said sergeant enters the room behind him. Tellingly, he never rises from the rank of private over the course of the film.