...steamer Philadelphia, Savannah River, January 4, 1865. Hon. Gideon Welles, Secretary of the Navy. Sir: I have already apprised the Department that the army of General Sherman occupied the city of Savannah on the 21st of December. The rebel army, hardly respectable in numbers or condition, escaped by crossing the river and taking the Union Causeway toward the railroad. I have walked about the c...