There may be some confusion here. The dates Ms. Sexton cites are July 28, 1864.

The 13th was engaged during the Battle of Gaines Mill on June 27, 1862.

They were then lightly engaged during the Battle of Glendale (Frasyer's Farm) on June 30, 1862.

If he was indeed wounded on July 28, 1864, it was likely in the First Battle of Deep Bottom.