Read the orders....better yet hear Bearss tell the story - it's amazing to hear him.
Selfridge said he was maneuvering to return fire from some rebel shore batteries. While Porter at first accused him of disobeying orders he later recanted. He was also on the Cumberland when the Virginia sank her, thus accounting for all three 'C' ships. Following the loss of the Conestoga he took command of the Osage, at the other end of the alphabetic spectrum.