This was an important promise by McClellan - since he failed to keep it, Lincoln got fed up and replaced him as General of the Army of the Potomac.
It was an interesting month. A couple of instances are recorded where rebs forced local merchants to trade their well-worn hats and other clothing items for newer models.
Their commanding officers forced them to return and either trade back or pay them the fair market value for the difference.
Quite the contrast to how Sherman's army treated the civilians in Georgia the following year.