What did Shad write that he was questioning of McClellan?

In Chapter Eight, Shad writes about the battle of Antietam and General McClellan. He writes that many of the soldiers worship General McClellan, but he is not one of them: "I tell you frankly that the contagion of their devotion has not yet gripped me. I do not dislike him...But he is afraid of something--of sending the men who love him to their death--of making an error that will reflect upon the image of himself which he knows to exist in the minds of his men. He does not have the cold approach to killing, the singleness of purpose, the brutal tenacity, that the winner of this war--if there ever is to be one--must have."