Waiting for the War
One of the major themes of the play is the soldiers all waiting for the war to come. There is a heightened degree of tension that is created because of this. Some are ready to fight, to stand for something like Billy and others are ready to do anything to stay alive, including killing their own like Carlyle.
Race
Race is a major theme of this play. We see the relationships between Billy and Roger contrasted with Carlyle and Richie. Rabe peels back layers for us to understand that though these men are in the same barracks they are from vastly different upbringings which leads to an inability to truly understand one another.
Homosexuality in the Military
This is a major theme of the film and one of, if not the primary topics of discussion throughout the play. Richie's sexuality, and even Billy's is called into question along with Carlyle who is open about wanting to participate in having sex with Richie. He doesn't seem to care who is around or watching. What makes this theme stand out even more is that Billy becomes the military's stance on gay's in the service. Billy believes he is standing up for his country, doing his duty by disallowing Richie and Carlyle from having sex.