It is the enduring paradox of our centuries here.

It is the paradox that stood its ground at Bunker Hill, paradox that made a doomed charge on Fort Wagner, paradox that stormed San Juan Hill, advanced through the Meuse-Argonne, landed on Iwo Jima, liberated Seoul and was taken prisoner in Hanoi.

It is the paradox: black men, will you defend America? Leave skin and blood in foreign lands fighting for ideals that do not include you?

Ideals like, We hold these truths to be self-evident that all men are created equal.

And, One man, one vote.

And, Liberty and justice for all.

That paradox suffuses "For Love of Liberty," a moving new documentary airing this month — Black History Month — on PBS. The program is a valuable compendium of black military history. Through narration and dramatic readings, a host of prominent actors — Halle Berry, Avery Brooks, Ice-T, John Goodman, Robert Duvall, Charles S. Dutton, LeVar Burton, Louis Gossett Jr., Susan Sarandon, Mel Gibson, Bill Cosby and many more — recreate the often incomprehensible bravery of black men and women who answered when their country called.

We get the runaway slave Crispus Attucks becoming the first person to die for American independence, and 5-foot-4 130-pound Pvt. Henry Johnson single-handedly driving off two dozen German attackers. We get Staff Sgt. Ruben Rivers, broken bone poking through his skin, refusing to be evacuated, refusing morphine, and leading his men against the Nazis in a battle that took his life. We get Pvt. Milton Olive throwing himself on a grenade in Vietnam. We get tombstones, reminding us that freedom bears a price.

But over, amid and above all that, we get the paradox.

One story paints the picture: It seems that during the Second World War, a group of nine African-American Marines in full uniform were traveling by train through Louisiana. They were denied service in the dining area of a local cafe, given sandwiches and sent to eat them in a room off the kitchen. As they ate, the men watched through the window as German prisoners of war and the white soldiers guarding them entered the same dining area to be seated and served.

As one of the black men asked in a letter to a military magazine: "What is the Negro soldier fighting for? On whose team are we playing? I stood outside looking in, but could not help to ask myself these questions. Are these men sworn enemies of this country? Are we not American soldiers sworn to fight and die, if need be, for this, our country? Then why are the Germans treated better than we are?"

From time to time in this country, one hears people — sometimes implicitly, sometimes explicitly — question the patriotism, the "American-ness" of African-American people. We heard this most recently during the racially charged campaign of 2008 when some said Michelle and Barack Obama and, by extension, those of us who look like them, were insufficient in their love of country, lacking in fealty to its highest ideals.

It is always ... enlightening to be lectured on love of country by those whose heritage includes no paradox. One hopes a few of them will chance upon this program.

One hopes they will see the stories of valor, linger upon the tombstones, watch American Marines denied seating at a table to which even Nazis are welcome, and marvel at the sheer love of country this bespeaks. Not love for the country as it is, but love for what it could someday be.

One hopes they will understand how much such love it takes to defy the paradox. Black men, it asks, will you defend America? Leave skin and blood in foreign lands fighting for ideals that do not include you? And always, the answer has been the same.

Yes.