What happen with the showcases Natalie Portman

“Jackie” is a profile in courage.

Its hero doesn’t carry a gun. She isn’t even in uniform — unless you count the pink suit and pillbox hat.

But she does wage a war, for her husband’s legacy, and to hasten her country’s healing in the aftermath of his death.

Natalie Portman stars as Jackie Kennedy in a film that looks at the worst four days in her life — from a Friday in Dallas that ends with her cradling her dying husband, to a Monday in Washington that begins with his funeral procession.

Portman’s been a committed, in-the-moment actress since she was a skinny kid running after “Leon: The Professional” but “Jackie” is an accomplishment on the Oscar-winning order of “Black Swan.” She gets the former First Lady’s breathy voice, her quiet style — and ever-present, barely-held-in-check nervousness.

And Pablo Larrain’s movie shows just what the real Jackie Kennedy had to deal with that November — a new President itchy to take over, powerful in-laws who had their own idea on how to grieve and a nation that didn’t know what would come next.

And so Jackie shows them — by crying in private, holding her head high in public and gently, firmly, bringing us all along with her on that long walk to Arlington National Cemetery.

As expert as Portman is, the rest of the cast settles for approximations. Peter Sarsgaard gets some of Bobby Kennedy’s feistiness, but he doesn’t really sound or look like him. If someone didn’t call him by name, you’d never guess that John Carroll Lynch was supposed to be playing LBJ.

Better is Billy Crudup, playing a journalist who, weeks later, has gone to Jackie Kennedy for “the truth.” Except she knows what the nation needs is a myth. And while she’s reluctant to talk about the assassination itself (which the film eventually recreates, in gruesome detail) she is intent on beginning the legend of Camelot.

The perfectly exact White House sets help her do that here, while Mica Levi’s throbbing orchestral score adds the proper funereal tone. And whenever the movie begins to falter — it cuts, sometimes confusingly, among at least three different timelines — Portman pulls it back together, and sets it back on course.

Which, of course, is what Jackie herself did for an entire country — all those impossibly distant, different years ago.