In Wheat's Battalion alone, of the 390 soldiers listed as being present in August 1861, a full 239, well more than half, were on the sick rolls.
Lang Son is the capital of Lang Son Province, home to nearly 2,400 soldiers listed as missing from the war.
However, a subsequent Pentagon report, released internally, disclosed that of the 312 soldiers listed as wounded, 72 were injured in parachute jumps.
She was not among the seven American soldiers - including five from the 507th - formally listed as prisoners of war.
Many of the families had been bracing for the possibility that the soldiers, previously listed as missing, had been killed.
They are the last soldiers listed on the timeline of the Vietnam Veterans Memorial located in Washington, D.C.
In addition, during his stay from April 5 to 9, he will make inquiries about the fate of American soldiers still listed as missing in action since the Vietnam War.
In the darkness and with his wife, Barbara, by his side, the President read aloud the names of some of the fallen soldiers listed on the shiny black granite wall.
He reported that most of the 311 soldiers listed as missing in action were believed to have been captured by guerrillas or to have deserted.
Eleven of the 41 soldiers listed on the Bellaire monument fought for West Virginia units instead of Ohio.