Since he advanced after most of his victories you must be referring to the Seven Days. McClellan's army had been turned and the lines of communication cut. There were two possibilities; change base or be destroyed. He successfully changed base whilst inflicting more casualties than inflicted. A superbly executed task, but one in which "advancing" was actually impossible without losing the army. Grant faced with the same situation at Holly Springs did exactly the same.
I know that its impossible for an army lead by McClellan to actually make a Confederate army do what he wants it to do rather than being forced by the Confederate army to do what its commander wants him to do, but advancing was very much possible and very much unlike Holly Springs.
Of course, that would have required a general who wasn't more afraid of Lee's ineffectual pounding on Porter than aware of what he could do to keep Lee from attacking him, since it would require thinking of how to harm the enemy - something McClellan seems to have been incapable of in the Seven Days.
http://www.civilwarhome.com/richardsonsevendayor.htm Doesn't sound like someone who feels the army is threatened in the way suggested, does it?
Reading Fitz-John Porter's account would be interesting, as well.
But from McClellan we have the following, which is damning:
From
http://ehistory.osu.edu/osu/sources/recordView.cfm?Content=012/0051
I have just heard that our advanced cavalry pickets on the left bank of Chickahominy are being driven in. It is probably Jackson's advance guard. If this be true, you may not hear from me for some days, as my communications will probably be cut off.
The case is perhaps a difficult one, but I shall resort to desperate measures, and will do my best to outmaneuver, outwit, and outfight the enemy. Do not believe reports of disaster, and do not be discouraged if you learn that my communications are cut off, and even Yorktown in possession of the enemy. Hope for the best, and I will not deceive the hopes you formerly placed in me.
Bold language (pun not intended). Now let's see how his behavior a month later when facing Lee's counter-offense compares to the text in bold:
From
http://ehistory.osu.edu/osu/sources/recordView.cfm?Content=012/0053 A change of base to meet a threat - it hasn't actually happened yet, but in order to prevent it he's choosing to pull back. Heaven forbid that the Army of the Potomac be used to prevent the enemy from being able to take advantage of the opportunity by virtue of pushing against Lee and forcing him to worry about his defenses. Oh no.
And in a striking display of "Hey these look close to the actual figures":
http://ehistory.osu.edu/osu/sources/recordView.cfm?Content=012/0056
Specifically, how he refers to Porter having about 35,000 vs. about 70,000. So that means that if the Army of Northern Virginia is ~100,000 men strong,
only thirty thousand menare present to threaten the rest of the Army of the Potomac, which means...why isn't McClellan attempting to put pressure on that third of Lee's army with the part of his army not with Porter? Surely if most of Lee's army is tied up facing Porter there's at least the opportunity to make him worry about what McClellan is doing if the latter acts aggressively.
What happened to the month ago statement of his intent to "outmanuever, outwit, and outfight"? It transformed into "I liked the James better anyway so I'm retreating to use it as a supply line rather than defend the one I have."
Thomas spent much of 1862 complaining about how raw the troops were. There are a lot of parallels to be drawn between Thomas and McClellan (and Buell, Rosecrans, Meade etc.). These competent but shrude generals often came acropper due to the civilians misplaced idea in the ease of pursuing a defeated but unbroken enemy. Remember the same civilians who fired McClellan, Buell and Rosecrans also agitated for the removal of Meade and Thomas.
I'm assuming shrude is shrewd, what is acropper?
I'm not sure how you can compare Thomas's record to McClellan's when McClellan has more to work with and less to show to his credit.
You can draw parallels in a vague sort of way between Thomas and McClellan, but comparing the guy who broke the AoT as an army to any Union general except Grant is not going to look good for the other guy.
In an effort to not completely derail this, I think McClellan's behavior on the Peninsula indicates an area that he and Davis would be unable to tolerate each other.
I'd like to think I'm not as narrow minded as Davis (though a degree of that is one of my faults), and my reaction to McClellan's reports is somewhere between suspicious and hostile.