Throughout the morning of July 20, the Army of the Cumberland crossed Peachtree Creek and began taking up defensive positions.
The XIV Corps, commanded by Major General John M. Palmer, took position on the right.
The XX Corps, commanded by Major General Joseph Hooker (the former commander of the Army of the Potomac who had lost the Battle of Chancellorsville) took position in the center.
The left was held by a single division (John Newton's) of the IV Corps, as the rest of that corps had been sent to reinforce Schofield and McPherson on the east side of Atlanta.
The Union forces began preparing defensive positions, but had only partially completed them by the time the Confederate attack began.

The few hours between the Union crossing and their completion of defensive earthworks were a moment of opportunity for the Confederates.
Hood committed two of his three corps to the attack: Hardee's corps would attack on the right, while the corps of General Stewart would attack on the left as the corps of General Benjamin Cheatham would keep an eye on the Union forces to the east of Atlanta.

Hood had wanted the attack launched at one o'clock, but confusion and miscommunication between Hardee and Hood prevented this from happening.
Hood instructed Hardee to ensure that his right flank maintained contact with Cheatham's corps, but Cheatham began moving his forces slightly eastward.
Hardee too began side-stepping to the east to maintain contact with Cheatham, while Stewart began sliding eastward as well in order to maintain contact with Hardee.
It was not until three o'clock that this movement ceased.

The Confederate attack was finally mounted at around four o’clock in the afternoon.
On the Confederate right, Hardee's men ran into fierce opposition and were unable to make much headway, with the Southerners suffering heavy losses.
The failure of the attack was largely due to faulty execution and a lack of pre-battle reconnaissance.

On the Confederate left, Stewart's attack was more successful.
Two Union brigades were forced to retreat, and most of the 33rd New Jersey Infantry Regiment (along with its battle flag) were captured by the Rebels, as was a 4-gun Union artillery battery.
Union forces counterattacked and after a bloody struggle, successfully blunted the Confederate offensive.
 Artillery helped stop the Confederate attack on Thomas' left flank.

A few hours into the battle, Hardee was preparing to send in his reserve, the division of General Patrick Cleburne, which he hoped would get the attack moving again and allow him to break through the Union lines.
An urgent message from Hood, however, forced him to cancel the attack and dispatch Cleburne to reinforce Cheatham, who was being threatened by a Union attack and in need of reinforcements.

The Union lines had bent but not broken under the weight of the Confederate attack, and by the end of the day the Rebels had failed to break through anywhere along the line.
Hood withdrew into defenses of Atlanta the following day, 21 July.
Estimated casualties were 4,250 in total: 1,750 on the Union side, including McPherson, and at least 2,500 on the Confederate.
Throughout the morning of July 20, the Army of the Cumberland crossed Peachtree Creek and began taking up defensive positions. The XIV Corps, commanded by Major General John M. Palmer, took position on the right. The XX Corps, commanded by Major General Joseph Hooker (the former commander of the Army of the Potomac who had lost the Battle of Chancellorsville) took position in the center. The left was held by a single division (John Newton's) of the IV Corps, as the rest of that corps had been sent to reinforce Schofield and McPherson on the east side of Atlanta. The Union forces began preparing defensive positions, but had only partially completed them by the time the Confederate attack began.
The few hours between the Union crossing and their completion of defensive earthworks were a moment of opportunity for the Confederates. Hood committed two of his three corps to the attack: Hardee's corps would attack on the right, while the corps of General Stewart would attack on the left as the corps of General Benjamin Cheatham would keep an eye on the Union forces to the east of Atlanta.
Hood had wanted the attack launched at one o'clock, but confusion and miscommunication between Hardee and Hood prevented this from happening. Hood instructed Hardee to ensure that his right flank maintained contact with Cheatham's corps, but Cheatham began moving his forces slightly eastward. Hardee too began side-stepping to the east to maintain contact with Cheatham, while Stewart began sliding eastward as well in order to maintain contact with Hardee. It was not until three o'clock that this movement ceased.
The Confederate attack was finally mounted at around four o’clock in the afternoon. On the Confederate right, Hardee's men ran into fierce opposition and were unable to make much headway, with the Southerners suffering heavy losses. The failure of the attack was largely due to faulty execution and a lack of pre-battle reconnaissance.
On the Confederate left, Stewart's attack was more successful. Two Union brigades were forced to retreat, and most of the 33rd New Jersey Infantry Regiment (along with its battle flag) were captured by the Rebels, as was a 4-gun Union artillery battery. Union forces counterattacked and after a bloody struggle, successfully blunted the Confederate offensive.  Artillery helped stop the Confederate attack on Thomas' left flank.
A few hours into the battle, Hardee was preparing to send in his reserve, the division of General Patrick Cleburne, which he hoped would get the attack moving again and allow him to break through the Union lines. An urgent message from Hood, however, forced him to cancel the attack and dispatch Cleburne to reinforce Cheatham, who was being threatened by a Union attack and in need of reinforcements.
The Union lines had bent but not broken under the weight of the Confederate attack, and by the end of the day the Rebels had failed to break through anywhere along the line. Hood withdrew into defenses of Atlanta the following day, 21 July. Estimated casualties were 4,250 in total: 1,750 on the Union side, including McPherson, and at least 2,500 on the Confederate.
Battle of Peachtree Creek