A Diary of American Events.

December 20.—The Third Wisconsin cavalry returned to Fort Smith, Ark., from a successful reconnoissance southward. They were within five miles of Red River, but finding that the rebels had changed position since last advices, they were unable to proceed further. Their return was a constant skirmish for over one hundred miles, strong bodies of the enemy being posted at all the cross-roads to intercept them. They, however, cut their way through. In some places they evaded the enemy by taking blind mountain-passes. Their loss was small.—Mrs. Anne Johnston, of Cincinnati, was tried at Nashville, Tenn., before the Military Committee, for acting as a rebel spy, and smuggling saddles and harness from Cincinnati into the rebel lines. The articles were packed in barrels, purporting to contain bacon, for the shipment of which permits had been regularly obtained.—The schooner Fox, tender to the United States flag-ship San Jacinto, East-Gulf squadron, destroyed in the Suwannee River, Florida, a rebel steamer, supposed to be the Little Leila, formerly the Paw-Paw, and before the Flushing. She was set fire to by a boat’s crew belonging to the Fox.—(Doc. 23.)