The exhibit, which opened July 4, details the service of the 593rd Field Artillery in Bougainville, New Guinea, and the southern Philippines.
They were commanded by Col. Joseph B. Phillips, Jr., a Hattiesburg native who had been in the Mississippi National Guard prior to World War Two.
He served in the Guard again after the war and died in 1974.
The photos in the exhibit were part of a collection in his estate.
"These photographs have not been seen before," said Glenn Husted, arms and vehicle conservator for the Mississippi Armed Forces Museum. "They've been put away and this is the first public viewing that we're aware of since the end of World War Two," he said.
"(The exhibit is) great, it's wonderful," said Claude Leaman, a museum visitor. "Anything that educates the next generation about the sacrifices that our soldiers made is wonderful," he said.
The exhibit will be on display through Aug. 8.