General Hazen's men of the Fifteenth Corps man a captured Confederate siege gun at Fort McAllister for the camera. Standing at attention above and facing the weapon is a U.S. Marine and beside him leaning on his saber is a cavalryman
As Sherman's armies neared Savannah on December 10, following their lengthy march from Atlanta, his troops were in need of supplies. Just off the coast was Admiral John A. Dahlgren's fleet waiting with the needed supplies, as well as mail that had not been delivered to Sherman's men for six weeks during their march. However, Confederate fortifications around Savannah prevented Dahlgren from linking up with Sherman. As Sherman deployed his forces to invest Savannah, his cavalry reconnoitered Fort McAllister and other nearby fortifications, and determined that the lightly defended fort could be taken by a determined infantry attack. Sherman realized that if Fort McAllister was reduced, the Union Army would control the Ogeechee River, providing an avenue to the sea. Sherman ordered Maj. Gen. Oliver Otis Howard's Army of the Tennessee to reduce the fort. Howard chose the division commanded by Brig. Gen.William B. Hazen to lead the attack.
On December 13, 1864, Hazen's 4,000-man division was deployed to storm the fort. Sherman and Howard climbed to an observation platform erected on top of an abandoned rice mill to observe the progress. In the surrounding woods Hazen formed his three brigades commanded respectively by Colonels Theodore Jones, Wells Jones and John M. Oliver. As the sun was setting, a Union Navy ship, USS Dandelion, steamed into view from Ossabaw Sound. Sherman signalled that the fort was still in enemy hands but would be theirs in a minute. Just then Hazen's men emerged from the woods and advanced towards the fort widely spaced apart to limit effectiveness of artillery. Confederate Major George Anderson commanded about 230 veteran troops in Fort McAllister. Hazen's troops charged through the abatis and buried torpedoes and soon reached the parapet and overwhelmed the defenders; the fort fell in 15 minutes.
Sherman was overjoyed with the victory and rowed down the Ogeechee to view the fort. The next day he rowed out to Dahlgren's flagship to greet the admiral. Sherman also had reason to be proud of the troops that had taken part in the victory at Fort McAllister. These were the same troops he personally led as a division commander at Shiloh and a corps commander at Vicksburg.
With his supply line now open, Sherman could now prepare for the siege and capture of Savannah, a goal he would achieve by Christmas.