From "Yes Man" to Hero
Sergeant Milton Warden (Burt Lancaster) is a complicated guy. On the one hand, he's tough—but he also doesn't want to step on his commanding officer's toes (despite despising him… and sleeping with his wife). In another movie, he'd be despicable. But in this one, he's just all too human.
His toughness becomes more visible at the end of the movie, when Warden takes charge of the men and helps them shoot down a Japanese plane. At the beginning his tough-guy attitude emanates more through the way he talks, and through the physical presence of Burt Lancaster.
At the beginning of the movie, Warden goes along with Captain Holmes' plan to force Robert E. Lee Prewitt to box by giving him "The Treatment" (i.e. consistently abusing him). At one point, Holmes wants to court-martial Prewitt, but Warden suggests doubling up punishment instead. This might be preferable to a court-martial since that's a criminal trial—but it's still not exactly fair, right, or compassionate.
And Warden clearly feels like the whole "Treatment" thing is wrong—which becomes more obvious as the movie progresses. Overall, his actions seem to emanate more from his philosophy: in the army, the individual doesn't count—you need to obey the wishes of your officer, even if they are ridiculous. But Warden comes to see that it's really the soldierly principles of honor and fairness that matter… not blind obedience to a corrupt superior.
Later on, Warden acts nicer to Prewitt, and after Prewitt beats one of Holmes' cronies in a fight, Warden and Prewitt get drunk together and act like friends. So there aren't really any hard feelings, it seems.
At the same time, Warden starts conducting an affair with Captain Holmes' wife, Karen. After paying a visit, and hitting on her at home, Warden meets up with Karen at the beach. She initially seems a little resistant—but gives in when they have the following exchange:
WARDEN: You think I'd be here if I thought it was a mistake? Taking a chance on twenty years in Leavenworth for making dates with the company commander's wife? And her acting like—like Lady Astor's horse, and all because I got here on time!
KAREN: Well, on the other hand, I've got a bathing suit under my dress…
WARDEN: Me too!
This conversation is basically the Oahu equivalent of "let me slip into something a little more comfortable."
Making Out, and Making Movie History
They then share an iconic movie moment, making out on the beach as a wave crashes over them. But this ain't happily ever after in Hawaii—Warden starts to act all uneasy about Karen's romantic career. She's apparently had other affairs before, and Warden seems put off by this.
When she explains her open relationship with the adulterous Capt. Holmes, and how he was responsible for her stillborn child, Warden softens up. He gets that her affairs are the byproduct of loneliness and a search for something real—which is what Warden is looking for too. Aww, those crazy kids. They continue to sneak around, carrying out their affair on the sly.
Karen Holmes wants Warden to apply to become an officer, so she can marry a man who's a bit more well off—once she divorces Holmes. But Warden isn't crazy about becoming an officer. He knows what he's good at, and that's being a sergeant. When the Pearl Harbor invasion happens, Warden takes charge, demonstrating his flair for combat and his leadership skills.