I did not want to make a mistake like "Ball's Bluff" at that period of the war; so, taking one or two of my personal staff, I rode back to Grog's Bridge, leaving with Generals Howard and Slocum orders to make all possible preparations, but not to attack, during my two or three days' absence; and there I took a boat for Wassaw Sound, whence Admiral Dahlgren conveyed me in his own boat (the Harvest Moon) to Hilton Head, where I represented the matter to General Foster, and he promptly agreed to give his personal attention to it.

During the night of the 20th we started back, the wind blowing strong, Admiral Dahlgren ordered the pilot of the Harvest Moon to run into Tybee, and to work his way through to Wassaw Sound and the Ogeechee River by the Romney Marshes.

We were caught by a low tide and stuck in the mud.

After laboring some time, the admiral ordered out his barge; in it we pulled through this intricate and shallow channel, and toward evening of December 21st we discovered, coming toward us, a tug, called the Red Legs, belonging to the Quarter-master's Department, with a staff-officer on board, bearing letters from Colonel Dayton to myself and the admiral, reporting that the city of Savannah had been found evacuated on the morning of December 21st, and was then in our possession.

General Hardee had crossed the Savannah River by a pontoon-bridge, carrying off his men and light artillery, blowing up his iron-clads and navy-yard, but leaving for us all the heavy guns, stores, cotton, railway-cars, steamboats, and an immense amount of public and private property.
Admiral Dahlgren concluded to go toward a vessel (the Sonoma) of his blockading fleet, which lay at anchor near Beaulieu, and I transferred to the Red Legs, and hastened up the Ogeechee River to Grog's Bridge, whence I rode to my camp that same night.