Past the rack of pistols at the Tennessee Civil War Museum, and past the video on firing a cannon, is a grainy 1861 photo of Andrew and Silas Chandler.

Both wear Confederate gray. Both hold swords in their right hands and guns in their left. But this is no ordinary picture of Southern loyalists. Silas is black, and Andrew is his white master.

The photo is part of a display stating that at least 35,000 blacks fought in the 1.2 million-man Confederate army. The claim is politically loaded, and, according to some historians, bogus.

"The numbers are vastly over-inflated," said William Blair, director of the Civil War Era Center at Pennsylvania State University. "There are people who want to distance slavery as the cause of the war. This feeds nicely into that whole view."

Craig Hadley, who designed the privately owned museum, believes critics balk because the issue challenges their narrow views of the South. That's why he included the display when the Chattanooga site opened last year.

"Nobody wants to acknowledge these people because they 'fought on the wrong side,' " said Hadley, a professor at Southern Adventist University.

Historians agree that some blacks enlisted as Confederates, even though the South banned them from the army until the desperate few months before the war ended. No one knows for sure how many joined or why.

The debate is rooted in the thousands of free men and slaves who served the South as laborers, cooks and musicians. Many were so-called body servants--slaves like Silas Chandler who traveled with their owners as personal attendants.

They may have been armed and may have used their guns for protection. Does that make them soldiers?

John McGlone, president of Southern Heritage Press and an editor of the journal "Black Southerners in Gray," says yes, even if their masters forced them into the war. McGlone believes more than 50,000 blacks fought for the South.

"When you do get a battle commencing it all becomes a big blur," said McGlone, a history lecturer at Motlow State Community College in Tullahoma. "Often, they got involved in battles even though their normal role was support."

Civil War historian James McPherson called McGlone's estimate absurd.

He puts the number between several hundred and a few thousand, saying laborers fought only under extraordinary circumstances.

"I would say that while the distinction was blurred around the edges, it was still a distinction," said McPherson, author of the Pulitzer Prize-winning book, "Battle Cry of Freedom."

Ervin Jordan, a University of Virginia associate professor, is the author of "Black Confederates and Afro-Yankees in Civil War Virginia," which Blair and other historians consider the most credible research on the topic.

Jordan said he can't estimate how many blacks joined up, though he said he would define a soldier as anyone who "actually took up firearms and shot at Yankees or helped catch Union soldiers."

"There are cases on file of black servants being permitted to join soldiers on a case-by-case basis," he said.

He does have some theories about why they fought.

Many thought of themselves as Southerners first, he said, and perhaps believed they would be given money, land or even their freedom in exchange for fighting.

Some may have felt loyal to their owners or pretended to be loyal to join the troops and plot an escape, he said. Others may have been influenced by talk of undisciplined Union soldiers mistreating blacks on their march.

Then there's the case of free blacks, like the Louisiana Native Guards. They were relatively prosperous New Orleans landowners of mixed-race heritage who volunteered in 1861 to fight for the Confederacy.

But after the North took control of the city the next year, the regiments reversed course, volunteering for the Union. McPherson said this indicates they fought to protect their property.

More research could simply raise more questions.

War records are sparse, identifying some soldiers by nothing more than their initials.

Newspaper accounts aren't reliable because some journalists wrote far from the battle sites, basing their stories on information from soldiers as they returned to camp, McPherson said.

Documents from burial details also are questionable. Crews often reported finding "Negro corpses" when the bodies simply had turned black after hours in the sun, McPherson said.

False stories have been repeated over the years and taken for true.

Jordan traced the origin of one well-known account of Southern troops at Gettysburg marching with a "colored flag bearer." It turned out the witness actually saw a "flag bearer bearing the colors," Jordan said.

Documents kept by Confederate states after the war make the record murkier.

Veterans' pensions were awarded to hundreds of blacks who were classified as laborers. Yet some who saw combat may have been forced to conceal their true role since officially they had been banned from the army. Jordan said he found documents where blacks had crossed out "soldier" and written "body servant" instead.

Major historical sites including the National Museum of the Civil War Soldier in Petersburg, Va., the Museum of the Confederacy in Richmond and Gettysburg National Military Park have no exhibits on black Confederate soldiers and no plans to add such displays.

"It would be something that we would probably address if there was evidence there were substantial numbers," Gettysburg historian Scott Hartwig said.

Jordan, who is black, won't join those groups--mainly white, he said--interested in erecting monuments to blacks in gray. "My attitude about blacks who were loyal to the Confederacy is I don't condemn them nor do I praise them," he said. "My goal is to explain them."

Hadley, who is white, said reaction to his Chattanooga exhibit ranges from praise to virulent condemnation. He expected as much when he developed the display and hopes it will generate more discussion.

"It's not something we need to be politically correct about," Hadley said. "We love to talk about the Civil War in general terms like the whole war was about ending slavery. The war was a whole lot more complex than that."