Smartass child of privilege John Payne is sent to Marine boot camp to learn about responsibility and being a team player. Although shot on location at San Diego, the sunny Technicolor training exercises look more like a musical-comedy summer stock company working out. Drillmaster Randolph Scott and fiery-haired nurse Maureen O'Hara love Payne in spite of his myriad obnoxious qualities, and he does have the right stuff, as he demonstrates at the drop of a hat--and the rest of his civilian clothes--the minute he hears about Pearl Harbor over the radio. The finale, a troopship embarkation turned full-scale production number, has to be seen to be disbelieved.
Titled after a lyric in the Marines' Hymn, which contains the phrase "... to the shores of Tripoli" (which is, itself, a reference to the Battle of Derne) the film is one of the last of the pre-Pearl Harbor service films. When the film was in post-production the Pearl Harbor attack occurred having the studio shoot a new ending where Payne re-enlists.
Wealthy Culver University drop-out and playboy Chris Winters (John Payne) enlists in the U.S. Marine Corps as a private where he meets his drill instructor Gunnery Sergeant Dixie Smith (Randolph Scott) and falls in love with a Navy Nurse, Lieutenant Mary Carter (Maureen O'Hara). Smith is given a letter from Winters' father. Captain Christopher Winters (Minor Watson) writes Smith of his playboy son. Sgt. Smith served in World War I under the elder Winters; Smith affectionately calls Winters "The Skipper". Chris Winters can not understand that Officers and Enlisted Men do not associate under the non-fraternization policy, even if the officer is a woman and the enlisted man is a male.
Chris' society girlfriend Helene Hunt (Nancy Kelly) wants Chris to get a cushy civilian job in Washington, D.C. and uses her uncle's power and her influence on the base commander, General Gordon. In sequences filmed at the Marine Corps Recruit Depot San Diego, Smith gives the younger Winters an opportunity to demonstrate his leadership potential by drilling his platoon. To Smith's amusement the Marines mock Chris and perform slapstick antics during the drill as Winters marches them away. As Smith is enjoying himself the platoon marches back and performs close order drill of a high order of perfection. Smith is greatly surprised until he looks over the platoon and notices several Marines have black eyes, chipped teeth and bruises. Chris Winters says, "I was captain of the boxing team at Culver."
Winters is selected for Sea School and on gunnery practice during naval maneuvers he bravely saves Dixie Smith's life when repairing gunnery targets. Chris picks a fight with Smith. However, Smith claimed he struck the first blow, by being busted in rank Smith will save Chris from the Naval Prison. Despite winning the respect of Dixie Smith and his fellow Marines, Chris decides to leave the Marines. But then he hears the news of the Pearl Harbor attack when driving in a car with Helene. His way is blocked by his old platoon marching to a Navy transport ship. Chris Winters runs to Sgt. Dixie Smith to reenlist; Chris enters the ranks that close up as he dresses in his old uniform from his satchel, he tosses away his civilian clothes and is in uniform except for his two-toned shoes. Chris's proud father, (Watson) wounded in World War I, asks his son to "Get a Jap for me".