To answer some of your questions. I have been searching for more information on Benedict, myself-without a lot of luck. I will post those as I find them. As for why he's there-it's probably one of those bureaucratic glitches-it says Corps d'Afrique-ie-his name got on.

Synopsis of events. On December 8th, 1863, Benedict was transferred from Ft. Philip to Ft. Jackson (They were across the river from each other-very close.)Some of the members of the 4th Corps were also transferred, and knew of/had suffered from his heavy handed punishments there. On the first day he was at Jackson, he had two drummer boys whipped for minor infractions (exact nature unknown)and members of the Corps became very agitated, shooting off some guns in the air, etc. The whole thing was quieted down within half an hour-but the gunfire had alerted gunboats in the area, and rumors flew.
Reports went to New Orleans-among them a now missing report from Col. Drew, Commander of the post. General Banks was furious, as these soldiers had been told repeatedly there would be no whippings or other "cruel and unusual punishments." Benedict tried to resign his post to Banks, but was refused. The resulting investigation and court martial proved him guilty without any doubt and he was "discharged the service." Among other incidents he was proven guilty of were several occasions where he had men staked out in the sun all day, covering their bare hands and feet in molasses-sometimes leaving them there for days at a time. (You can imagine the heat, thirst-and the insect activity.)Many incidents of striking, whipping, and other physical abuse while he was at Ft. Philip.

The official records are incomplete, and I have many details to fill in-but this poor excuse for a human being does not belong on the monument. More on him later.