Not really surprising, with so many thousands of wounded left after the battles.
There are many stories of soldiers going home to die, rather than waiting to die in the disease-ridden death camps called “Field Hospitals” in those days.
These likely would not have been accounted for.
Union Major General Joshua Chamberlain, of Gettysburg and Appomattox Courthouse fame, died of his wounds in February 1914, almost sixty years after receiving them at Petersburg in the summer of 1864.
Just a few years ago, a Vietnam vet died of the lingering effects of his wounds, some forty years after receiving them, and his name was added to the Vietnam Wall.
The list could go on and on; the WW1 submariners who almost all died before 1950 because of the chemicals in their confined spacing, the doughboys, Tommies, and their other counterparts, who lingered on for years after being gassed in the trenches; and the POW's who died as a result of the malnutrition and abuse they received in the camps.