LAURA BARRON-LOPEZ: 80, years ago, 320 people were killed in a massive explosion at a navy munitions depot in Port Chicago, California.

About two-thirds of the people killed were black sailors who loaded bombs and ammunition onto ships.

50 survivors refused to resume handling the explosives and were convicted of mutiny.

Last month, the Navy Secretary posthumously exonerated the men who became known as the Port Chicago 50.

Ali Rogin has more.

ALI ROGIN: The Port Chicago explosion was World War II's deadliest stateside disaster.

It's also a blistering example of racism, negligence and injustice in America.

Steve Sheinkin wrote about all of it in his young adult book, "The Port Chicago 50: The Disaster, Mutiny, and the Fight for Civil Rights," and he joins me now.

Steve, thank you so much.

The death toll at Port Chicago represented 1/5 of all African American World War II naval casualties take us back to that day.

What was it like for black sailors at Port Chicago?

STEVE SHEINKIN, Author, "The Port Chicago 50: The Disaster, Mutiny, and the Fight for Civil Rights": This was a loading a base, a naval base in the Bay Area of San Francisco Bay, and all they did was load ammunition, and it was totally segregated, like all of the Navy was during World War II.

So Black sailors, many of them teenagers, were assigned to this base and loaded ammunition in three shifts, 24 hours a day.

They understood about the racism in the country at the time, of course.

But they also knew that it was unnecessarily dangerous, that they had been given the proper training, and that something horrible was eventually going to happen.

And sure enough, there was this huge explosion, two full ships, thousands of tons of ammunition exploded, killing over 300 people.

ALI ROGIN: And when these men were charged after they refused to return to loading ammunition, they were charged with mutiny, which carries the possibility of execution.

Why did they receive that charge?

STEVE SHEINKIN: Well, it happened over the course of a couple weeks.

First, they were given the gruesome task of cleaning up the base, finding bodies, but mostly parts of bodies.

And they were taken to another base in the Bay Area and not told anything about what they were going to be doing.

And sure enough, a couple weeks later, they were marched down toward the loading dock to begin loading again.

And at first, about 250 of them refused to go.

And they were taken to a prison barge.

Then after three days on the barge, they were taken in a very dramatic scene, taken to a baseball field, and an admiral came out yelling at them and telling them they were all going to be charged with mutiny if they didn't go back to work right away.

Half of them were teenagers.

They had a second or two to decide, do I go back to work?

Do I go back to these conditions that I know are unfair, or do I take a stand?

And understandably, most of them went back 50.

This is where the term Port Chicago 50 came from.

50 of them refused, and they were indeed charged with mutiny and told point blank, told that they were going to be executed by a firing squad.

ALI ROGIN: There was also a court of inquiry into this explosion.

Did this court treat black soldiers differently than it treated the white officers who were overseeing them in these roles?

STEVE SHEINKIN: Yes.

For instance, the white officers got lead after this horrible disaster, and the black sailors did not but also the Navy didn't really know.

To this day we don't know exactly what happened, what went wrong, some sort of accident or malfunction, but it was clearly implied that it was, quote, rough handling by these sailors who had told their officers, hey, we're not being trained.

This is the kind of work that takes years of training.

There's not even a train, even a training manual.

Can you give us better equipment?

And they were always denied that at every turn.

ALI ROGIN: And after the trial, what penalties did these 50 men experience?

STEVE SHEINKIN: These 50 men were all convicted of mutiny.

They were not given the death penalty, though that was legally possible.

They were all sent to a military prison for sentence to 15 years.

They didn't end up serving all of that time, but that was the sentence that they were given.

ALI ROGIN: In 1999, President Clinton pardoned Freddie Meeks.

The family of others said that they weren't interested in pardons.

Why is that?

STEVE SHEINKIN: Several of the of the 50 men were still alive at that time, and they knew what Freddie Meeks was doing, and they supported his effort, but they said, That's not for us.

We're not asking for a pardon.

A pardon is when you did something wrong and you're asking to be forgiven for it or not punished for it.

And they said, No, that's not it at all.

That's almost exactly the opposite of what we're saying.

We're saying it was the government, the country, in a sense, that was wrong.

We want to be exonerated, so that the government admits we didn't do anything wrong.

And in fact, the injustice was on the other side.

ALI ROGIN: The military was desegregated not long after.

How did this incident help lead to that?

STEVE SHEINKIN: I think the most famous part of that story is Truman signing an executive order desegregating the whole military.

But in fact, it was the Navy, to their credit, that desegregated first, largely in response to what happened at Port Chicago and some other, as they would call them, racial incidents, where they said, this just isn't working.

The segregation isn't working.

Let's just try integrating ships, and for the most part, that went well, and so the rest of the military saw that, and essentially gave Truman the OK to sign that executive order.

But it largely came out of this stand that these young black sailors took at Port Chicago.

ALI ROGIN: This is such a sordid and significant chapter in American history.

Why do we not know more about this?

STEVE SHEINKIN: This is the summer of 1944 so you have to account for D-Day and all the things that are happening in Europe and the Pacific.

But also, I think there's a bigger issue, which is that it doesn't fit our American narrative of World War II, which we like to think of as a really simple story in terms of good and evil, in terms of the sides.

And we're not as good at understanding that, yes, that can be true.

We were fighting for good.

We were fighting very evil fascist and communist dictators.

That's absolutely true, and yet we were not, at the same time, living up to our ideals at home.

And these black sailors were, of course, a living embodiment of that.

They were telling everybody who would listen that.

And that doesn't exactly fit, or at least complicates our world war two story, and I think therefore it doesn't make it into the mainstream version of our history.

ALI ROGIN: Steve Sheinkin, author of the "Port Chicago 50: The Disaster, Mutiny and the Fight for Civil Rights."

Thank you so much.

STEVE SHEINKIN: Thank you.

Thank you for covering this important story.