To fully appreciate the strange mix of unintended comedy and real achievement in Tommy Lee Jones’ performance as General Douglas MacArthur, it helps to have some familiarity with MacArthur – the sonorous voice, the melodrama, the vanity, the swagger. Like Jones, he had a distinct way of speaking and plenty of attitude, but in neither was he anything like Jones.

This puts Jones in a strange box in “Emperor.” The actor’s only intrinsic connection to MacArthur is his own swagger, but his swagger is very much connected to the Southern accent and the bulldog stare, all the things that make him nothing like MacArthur. Yet here and there, he feels obligated to venture a word or two in the direction of sounding like MacArthur, and the results are usually comical, sometimes weird. Probably the best way to watch “Emperor” is to pretend that the Supreme Command of Allied Forces in Japan after World War II was Tommy Lee Jones. Once you do that, the movie works surprisingly well.

“Emperor” deals with a crucial chapter in postwar history, in which the future direction of Japan was being decided by MacArthur and a handful of advisers. The General appoints the Brigadier, Bonner Fellers (Matthew Fox) to investigate Emperor Hirohito for war crimes. The American public is clamoring for the Emperor’s head, but executing him could set back the occupation and open the door to the Soviets.

“Emperor” is a study in creating the illusion of drama. Fellers must find evidence to exonerate Hirohito, and the clock is ticking. Meanwhile the film keeps flashing back to give us bits of the romance Fellers once had with a Japanese student. No, it’s not “Romeo and Juliet,” but it’s enough to make us wonder how it worked out and if she’s still alive.

None of these elements is especially compelling, but together they keep “Emperor” on enough of a low simmer to stay interesting and allow us to appreciate other things. Fox, who’s the real star, plays Fellers as the sweetest, gentlest guy in the world in his private life. But in his professional life, he has the officer thing down: He’s abrupt, forceful and ungiving. It’s a smart, thought-through performance.

Meanwhile, if he could be resurrected long enough to see this movie, probably no one would be more surprised to see himself portrayed as a romantic hero than Bonner Fellers. For one thing, the Japanese girlfriend seems to have been the invention of the filmmakers. And after his military career – he was demoted from Brigadier General to Colonel by Eisenhower, who disliked him – Fellers got into extreme right-wing politics and even joined the John Birch Society.

We can take two lessons from this: 1) Someone can be dead-on correct about one thing and then turn out to be dead wrong about something else; and 2) Anyone can end up the hero of a movie.