Atlanta campaign

The Atlanta campaign was a series of battles fought in the Western Theater of the American Civil War throughout northwest Georgia and the area around Atlanta during the summer of 1864. Union Maj. Gen. William Tecumseh Sherman invaded Georgia from the vicinity of Chattanooga, Tennessee, beginning in May 1864, opposed by the Confederate general Joseph E. Johnston.

Johnston's Army of Tennessee withdrew toward Atlanta in the face of successive flanking maneuvers by Sherman's group of armies. In July, the Confederate president, Jefferson Davis, replaced Johnston with the more aggressive General John Bell Hood, who began challenging the Union Army in a series of costly frontal assaults. Hood's army was eventually besieged in Atlanta and the city fell on September 2, setting the stage for Sherman's March to the Sea and hastening the end of the war.

The Atlanta campaign followed the Union victory in the Battles for Chattanooga in November 1863; Chattanooga was known as the "Gateway to the South", and its capture opened that gateway. After Ulysses S. Grant was promoted to general-in-chief of all Union armies, he left his favorite subordinate from his time in command of the Western Theater, William T. Sherman, in charge of the Western armies. Grant's strategy was to apply pressure against the Confederacy in several coordinated offensives. While he, George G. Meade, Benjamin Butler, Franz Sigel, George Crook, and William W. Averell advanced in Virginia against Robert E. Lee, and Nathaniel Banks attempted to capture Mobile, Alabama, Sherman was assigned the mission of defeating Johnston's army, capturing Atlanta, and striking through Georgia and the Confederate heartland.

At the start of the campaign, Sherman's Military Division of the Mississippi consisted of three armies:

On paper at the beginning of the campaign, Sherman outnumbered Johnston 98,500 to 50,000, but his ranks were initially depleted by many furloughed soldiers, and Johnston received 15,000 reinforcements from Alabama. However, by June, a steady stream of reinforcements brought Sherman's strength to 112,000.

Opposing Sherman, the Army of Tennessee was commanded first by Gen. Joseph E. Johnston, who was relieved of his command in mid-campaign and replaced by Lt. Gen. John Bell Hood. The four corps in the 50,000-man army were commanded by:

Johnston was a conservative general with a reputation for withdrawing his army before serious contact would result; this was certainly his pattern against George B. McClellan in the Peninsula Campaign of 1862. But in Georgia, he faced the much more aggressive Sherman. Johnston's army repeatedly took up strongly entrenched defensive positions in the campaign. Sherman prudently avoided suicidal frontal assaults against most of these positions, instead maneuvering in flanking marches around the defenses as he advanced from Chattanooga towards Atlanta. Whenever Sherman flanked the defensive lines (almost exclusively around Johnston's left flank), Johnston would retreat to another prepared position. Both armies took advantage of the railroads as supply lines, with Johnston shortening his supply lines as he drew closer to Atlanta, and Sherman lengthening his own.

Johnston had entrenched his army on the long, high mountain of Rocky Face Ridge and eastward across Crow Valley. Sherman had earlier decided to demonstrate against the strong Confederate position with the bulk of his force while he sent a smaller portion through Snake Creek Gap, to the right, to hit the Western & Atlantic Railroad at Resaca, Georgia. With sufficient men, the Union Army could cut off the Confederate lines of communication to the south and force Johnston to attack them or disperse his army traveling through the rough terrain to the east. The larger Union force engaged the enemy at Buzzard Roost (Mill Creek Gap) and at Dug Gap drawing away their attention. In the meantime, the third column, under McPherson, passed unnoticed through Snake Creek Gap and on May 9 advanced to the outskirts of Resaca, where it found a small Confederate force entrenched. Fearing defeat, McPherson pulled his column back to Snake Creek Gap, which Sherman's orders gave him authority to do. On May 10, Sherman decided to take most of his men and join McPherson to take Resaca. The next morning, as he discovered Sherman's army withdrawing from their positions in front of Rocky Face Ridge, Johnston retired south towards Resaca. So began the first of a long series of flanking maneuvers by Sherman against Johnston; Sherman became so good at the tactic that his men boasted that Sherman "could flank the devil out of hell, if necessary." Johnston would be flanked out of every position he held until eventually relieved of command. The opportunity to destroy or disorganize the Confederates in the campaign's first battle, however, was missed.