Hmm, all I know about McClellan is that he was a Civil War general (and I don't even remember what game had the TCS McClellan?) - was there anything particularly controversial about him?
"Little Mac" ran for presidency against Lincoln in 1864, still being an active duty general (he resigned his commission on the day of election). Earlier, during campaign that ended in the battle of 2nd Manassas he delayed return of his army, because he wanted other Union general (Pope) defeated. Overall he was very "political" general who cared too much for his career.