TOKYO (Reuters) - On the night of July 17, 1944, an explosion with nearly the force of an atomic bomb ripped through the Port Chicago Naval Magazine north of San Francisco, killing 320 people - most of whom were African-American sailors loading weapons on ships.
Though the men had loaded ordnance essential to victory in the Battle of Saipan, which had just ended, the Navy blamed them for the explosion. When they refused to load the ships again, the Navy launched the largest mutiny trial in its history.
The ultimate conviction of 50 men became a cause célèbre, setting off accusations of injustice and racism that eventually became a catalyst for integrating the Navy and other armed forces, said historian and author James Campbell.
Yet even so, when he began the research several years ago that became "The Color of War - How One Battle Broke Japan and Another Changed America," he found almost no material.
"All of this black experience had been marginalized or overlooked," Campbell said in a telephone interview.
"Even now, they're talking about the hidden heroes of World War Two, and in many ways that's what they were. They performed ably and they performed essential roles, but they were given very little credit for what they did."
As Campbell found, the Port Chicago explosion and trial was in some ways the culmination of long, hard years during which African-American servicemen were allowed to enlist by armed forces reluctant to integrate despite outside pressure to do so - but were then assigned only menial tasks.
"At some point they realized that they could use all this African-American labor supply for the kind of jobs that the white soldiers didn't want to do. They brought them aboard and in some cases recruiters made promises that none of the branches of the services could live up to," he said.
"So some of these men went up with these illusions, which was the saddest thing. They went in very hopefully only to have their dreams dashed."
In particular, the top brass had no intention of sending African-American servicemen into battle, though in some cases - such as at Saipan - this did take place.
But by the time of the Korean War the services were largely integrated, much of this due to the social pressure prompted by the "blatant injustice" of Port Chicago.
"I think the resistance to integration created more problems than if they had just addressed it head on and said, 'we're integrating, you don't have to be friends, we expect you to act like comrades, like soldiers fighting for the same flag,'" Campbell said.
Recognition has come at last for veterans of the pioneering African-American Montford Point Marines, who will be awarded the Congressional Gold Medal this month - nearly 70 years after the war ended.
Campbell said he felt that Port Chicago still held relevance for today's armed forces, with parallels to how gays have been allowed into the military - and larger lessons as well.
"I think if they'd left it up to the individual men, it (integration) would have been much easier... I think that same attitude goes for just about anything," he said.
"Deception and resistance just creates a bigger problem than if something is addressed honestly and courageously."
(Reporting by Elaine Lies, editing by Paul Casciato)