20th.—A deep gloom hangs over the army to-day. I have at no time seen it so depressed—depressed not only at its new defeat, but at its own halting between opinions. Though the affection of the soldiers for Gen. Burnside was warm and active, it had not been confirmed by trials and experience, and the “expectant friends of Gen. McClellan” are still busy in taking advantage of this defeat to depreciate Gen. Burnside in the confidence of the army. This causes halting in opinions, and fears that our new Commander-in-Chief may not prove competent to the charge entrusted to him. It is of a piece with the McClellan tactics. Rule or ruin has been the motto of many of his friends.