Gen. Hooker, so far, has shown himself to be a chieftain, in the true sense of that term. He has done his utmost to bring up the spirit of the army, and his labor has been rewarded with the most gratifying success. The recent brilliant affair at Kelly’s Ford, where our cavalry rushed upon the foe, without firing a shot, and sabred the rebels in their intrenchments, is but one indication of the great change he has wrought. The utter worthlessness of our cavalry had long been the standing reproach of this army. “Who ever saw a dead cavalry man?” was the derisive interrogatory from every branch of the service. General Hooker resolved that this should cease. He said to a brigadier of cavalry: