Both U.S. President Abraham Lincoln and General Ulysses S. Grant had serious reservations about Sherman's plans. Still, Grant trusted Sherman's assessment and on November 2, 1864, he sent Sherman a telegram stating simply, "Go as you propose."

Sherman's personal escort on the march was the 1st Alabama Cavalry Regiment, a unit made up entirely of Southerners who remained loyal to the Union.

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The two wings of the army attempted to confuse and deceive the enemy about their destinations; the Confederates could not tell from the initial movements whether Sherman would march on Macon, Augusta, or Savannah. Howard's wing, led by Kilpatrick's cavalry, marched south along the railroad to Lovejoy's Station, which caused the defenders there to conduct a fighting retreat to Macon. The cavalry captured two Confederate guns at Lovejoy's Station, and then two more and 50 prisoners at Bear Creek Station. Howard's infantry marched through Jonesboro to Gordon, southwest of the state capital, Milledgeville. Slocum's wing, accompanied by Sherman, moved to the east, in the direction of Augusta. They destroyed the bridge across the Oconee River and then turned south.

The first real resistance was felt by Howard's right wing at the Battle of Griswoldville on November 22. Confederate Maj. Gen. Wheeler's cavalry struck Brig. Gen. Kilpatrick's, killing one, wounding two and capturing 18. The infantry brigade of Brig. Gen. Charles C. Walcutt arrived to stabilize the defense, and the division of Georgia militia launched several hours of badly coordinated attacks, eventually retreating with about 1,100 casualties (of which about 600 were prisoners), versus the Union's 100.

At the same time, Slocum's left wing approached the state capital at Milledgeville, prompting the hasty departure of Governor Joseph Brown and the state legislature. On November 23, Slocum's troops captured the city and held a mock legislative session in the capitol building, jokingly voting Georgia back into the Union.

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Sherman's armies reached the outskirts of Savannah on December 10 but found that Hardee had entrenched 10,000 men in favorable fighting positions, and his soldiers had flooded the surrounding rice fields, leaving only narrow causeways available to approach the city. Sherman was blocked from linking up with the U.S. Navy as he had planned, so he dispatched cavalry to Fort McAllister, guarding the Ogeechee River, in hopes of unblocking his route and obtaining supplies awaiting him on the Navy ships. On December 13, William B. Hazen's division of Howard's wing stormed the fort in the Battle of Fort McAllister and captured it within 15 minutes. Some of the 134 Union casualties were caused by torpedoes, a name for crude land mines that were used only rarely in the war.

Now that Sherman had contact with the Navy fleet under Rear Admiral John A. Dahlgren, he was able to obtain the supplies and siege artillery he required to invest Savannah.

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Hardee decided not to surrender but to escape. On December 20, he led his men across the Savannah River on a makeshift pontoon bridge. The next morning, Savannah Mayor Richard Dennis Arnold, with a delegation of aldermen and ladies of the city, rode out (until they were unhorsed by fleeing Confederate cavalrymen) to offer a proposition: The city would surrender and offer no resistance, in exchange for General Geary's promise to protect the city's citizens and their property. Geary telegraphed Sherman, who advised him to accept the offer. Arnold presented him with the key to the city, and Sherman's men, led by Geary's division of the XX Corps, occupied the city the same day.

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Sherman telegraphed to President Lincoln, "I beg to present you as a Christmas gift the City of Savannah, with one hundred and fifty heavy guns and plenty of ammunition and about twenty-five thousand bales of cotton."