I found a record on www.civilwardata.com that lists a Lewis T.Penneck (not Pennock) . That may be a typo, or their source, the "Roster of Wisconsin Volunteers, War of Rebellion" might have the typo.

States he was from Madison, enlisted 2-21-1862 into the WI 1st Cavalry, Company L, as a sergeant. He was mustered out 7-19-1865 in Edgefield, TN.

There was no WI 1st Veteran Cavalry.

The National Archives lists him as Lewis T.Pennock, enlisting as a private and promoted to "2nd duty sergeant".

I was unable to locate a single photo of anyone in this unit.