At Marine Headquarters in San Diego, a request is made for volunteers for a special battalion, one that will be trained for an overseas mission against the Japanese and calls for action "above and beyond the line of duty." The 15,000 prospective "raiders" include Southerner Rube Tedrow, minister John Harbison, troubled youth Frankie Montana, boxer "Pig-Iron" Matthews, and half-brothers Kurt Richter and Larry O'Ryan, who are rivals for the same girl. Meanwhile, the battalion's leader, Colonel Thorwald, tells his old friend, Leo "Transport" Andreof, that he had previously quit the Marines to join the Chinese army in their war against the Japanese. With the United States' entry into World War II, Thorwald returned to the Marines and plans to train his men in the same methods as those used by the Chinese. Upon his first meeting with the volunteers, Thorwald informs them that the battalion's motto will be the Chinese saying, "gung ho," which means to work in harmony, as teamwork will be required for their mission to be successful. The recruits are soon pared down to 900, and are put through vigorous physical training and taught various forms of self-defense, including judo. With their basic training completed, the remaining 600 Marines in the 2nd Raider Battalion ship out to Pearl Harbor in the South Pacific. Later, 210 of the men are sent on an eight-day submarine voyage to the Japanese-held South Sea island of Makin. As the submarines near the island, Thorwald tells his men that, though they will be severely outnumbered by the enemy, through careful planning, teamwork and surprise, they will be victorious. Their first contact with the Japanese happens after one of the submerging submarines is forced to resurface when the sleeping Rube is left topside just as three Japanese fighters appear on the horizon. They survive that encounter and soon arrive at Makin Island. The raiders land on the island at sunrise, and are quickly under fire from the Japanese. After Transport and Private Kozzarowksi are killed knocking out the Japanese radio transmitter, Thorwald has his men pull back and lure the Japanese soldiers to the hospital building. A squadron of Japanese planes then arrives at the hospital area, and, seeing the American flags the Marines have painted on the roofs of the buildings, attack and the majority of the Japanese soldiers are killed by their own aircraft. With the enemy defeated and the Japanese oil depot destroyed, Thorwald orders his men back to the submarines as Japanese ships approach. As the submarines head back to Pearl Harbor, Thorwald reminds his men of their thirty fellow Marines who died on the raid, including John and Larry, and how they have helped to pave the hard road to victory with their achievement at Makin Island.