Hi John,
Hobart Walker was a member of the 44th NY (Ellsworth) Regiment when he was captured during the battle of Malvern Hill on July 1, 1862. According to correspondence to Hobart's father Ferdinand, Hobart was last seen helping a wounded comrade from the battlefield and his whereabouts was unknown even as late as July 22, 1862. It was eventually realized he had been captured.
He was also wounded several months prior to that battle while on picket duty.
I obtained his military records for his time with the 106th NY from the government and they do have his name as Hubbard Walker.
My great-great grandmother was Hobart's sister. Her name was Emma Walker. She married a Coombs and had a daughter who was my grandfather's mother.
Best regards,
Jim