Ulysses S. Grant had been promoted to lieutenant general on March 9.

Three days later, President Abraham Lincoln appoints him General-in-Chief of the Armies of the United States.

In the spring of 1864, Grant sets in motion a grand strategy designed to press the Confederacy into submission.

"My primary mission," reasoned Grant, "is to ... bring pressure to bear on the Confederacy so no longer could it take advantage of interior lines."

Grant devises a strategy of multiple, simultaneous offensives against the Confederacy, hoping to prevent any of the rebel armies from reinforcing the others over interior lines.

The two most significant of these are to be led by Major General George G. Meade's Army of the Potomac, accompanied by Grant himself, which is to attack Robert E. Lee's army directly and advance toward the Confederate capital of Richmond, Virginia; and Major General William T. Sherman, replacing Grant in his role as commander of the Military Division of the Mississippi, who is to advance from Chattanooga, Tennessee, to Atlanta.

Both Grant and Sherman initially had objectives to engage with and destroy the two principal armies of the Confederacy, relegating the capture of important enemy cities to a secondary, supporting role.

This is a strategy that President Abraham Lincoln has emphasized throughout the war, but Grant is the first general who actively cooperates with it.

As their campaigns progress, however, the political importance of the cities of Richmond and Atlanta begins to dominate their strategy.

With Chattanooga and Vicksburg firmly under the control of the North by the end of 1863, Atlanta is now the logical point for Union forces to attack in their western campaign.

Distant from earlier fighting, Atlanta has become an important Confederate railroad, supply, and manufacturing center and a gateway to the lower South.

Atlanta has become a critical target.

The city of twenty thousand had been founded at the intersection of four important railroad lines that supply the Confederacy and is a military manufacturing arsenal in its own right.

Atlanta's nickname of "Gate City of the South" is apt—its capture would open virtually the entire Deep South to Union conquest.

Grant's orders to Sherman are to "move against Johnston's Army, to break it up and to get into the interior of the enemy's country as far as you can, inflicting all the damage you can against their War resources."

Grant begins his advance into Virginia while Sherman, a red-haired man who will gain a lasting reputation as a major architect of modern warfare, leaves Chattanooga with one hundred thousand men to begin his march through Georgia on May 5-7.

Sherman's force is composed of three subordinate armies: the Army of the Tennessee (Grant's and later Sherman's army of 1862–63) under Major General James B. McPherson; the Army of the Cumberland under Major General George H. Thomas; and the relatively small Army of the Ohio (composed of only the XXIII Corps) under Major General John M. Schofield.

Their principal opponent is the Confederate Army of Tennessee, commanded by Gen. Joseph E. Johnston, who had replaced the unpopular Braxton Bragg after his defeat in Chattanooga in November 1863.

The fifty thousand-man army consists of the infantry corps of Lieutenant Generals William J. Hardee, John Bell Hood, and Leonidas Polk, and a cavalry corps under Major General Joseph Wheeler.

Sherman launches demonstration attacks against Johnston's position on the long, high mountain named Rocky Face Ridge while McPherson's Army of the Tennessee advances stealthily around Johnston's left flank toward the town of Resaca and Johnston's supply line on the Western & Atlantic Railroad.

Unfortunately for Sherman, McPherson encounters a small Confederate force entrenched in the outskirts of Resaca and cautiously pulls back to Snake Creek Gap, squandering the opportunity to trap the Confederate army.

As Sherman swings his entire army in the direction of Resaca, Johnston retires to take up positions here.

The Confederate government had granted General Joseph E. Johnston's request for reinforcements to his camps around Dalton, Georgia, in early May 1864.

As the brigade of Brigadier General James Cantey had started to move through the city on May 7, cavalry scouts had alerted Johnston that a large number of Union troops were moving towards Rome, Georgia, on roads that led through Resaca.

During the remainder of May 7 and the day of May 8 Cantey's brigade has had time to entrench and set up defenses.

On May 9, the Army of the Tennessee, under the command of James B. McPherson, had moved out of Snake Creek Gap and immediately run into a Confederate cavalry brigade ordered to scout the area the day before under the command of Colonel Warren Grigsby.

After a fierce battle, Brigadier General Thomas W. Sweeny had formed a defensive line, driving the Confederates back to Resaca, several miles to the east.

Sherman's plan, as written in his memoirs, is to hold the railroad and telegraph lines south of Dalton, so that Johnston will either evacuate his position at Dalton or detach a section of his army to fight Sherman on a ground that has more of an advantage to Sherman.

He has devoted the Army of the Tennessee to this mission, while the Army of the Cumberland and the Army of the Ohio, commanded by George H. Thomas and John M. Schofield, respectively, will feign attacks in the Confederates' front.

As McPherson's two Corps leave the woods, they skirmish with Confederate cavalry for a while until the cavalry id able to withdraw to a line of fortifications on the outer edge of the city, where they are reinforced by the 37th Mississippi, a regiment in James Cantey's brigade.

In the evening, Sherman sends his only cavalry, the 9th Illinois Mounted Infantry, northeast to scout out the best route to the Western & Atlantic Railroad.

Meanwhile, skirmishers in Major General Grenville Dodge's XVI Corps move to attack a line of fortifications along Camp Creek, held by Confederate cavalry, the remainders of Cantey's brigade, two twelve pound Napoleonic-era batteries and a fresh brigade under Confederate brigadier general Daniel H. Reynolds, which is the lead of the column of twenty thousand men sent out from Atlanta by John Bell Hood.

Johnston had withdrawn his forces from Rocky Face Ridge to the hills around Resaca.

On May 13, the Union troops had tested the Rebel lines to pinpoint their whereabouts.

The next day, full scale fighting had occurred, and the Union troops had been generally repulsed except on the Rebel right flank, where Sherman had not fully exploited his advantage.

On May 15, the battle continues with no advantage to either side until Sherman sends a force across the Oostanaula River, at Lay's Ferry, using newly delivered Cumberland pontoon bridges and advances towards Johnston's railroad supply line.

Johnston, unable to halt the Union turning movement caused by Sherman's crossing of the Oostanaula, had been forced to retire, burning the railroad span and a nearby wagon bridge in the early morning of May 16.

After the Union repairs the bridges and transports more men over, they continue in the pursuit of the Confederates, leading to the Battle of Adairsville on May 17.

There are sixty-one hundred combined casualties: thirty-five hundred for the Union and twenty-six hundred for the Confederacy.

Johnston's army had taken up defensive positions at Allatoona Pass south of Cartersville, but Sherman had once again turned Johnston's left as he temporarily abandoned his railroad supply line and advanced on Dallas.

Johnston had been forced to move from his strong position and meet Sherman's army in the open.

Fierce but inconclusive fighting occurs on May 25 at New Hope Church, ...

...at Pickett's Mill on May 27, and ...

...at Dallas on May 28.

Heavy rains had turned the roads to quagmires by June 1 and Sherman had been forced to return to the railroad to supply his men.

Johnston's new line (called the Brushy Mountain Line) had been established by June 4 northwest of Marietta, along Lost Mountain, Pine Mountain, and Brush Mountain.

On June 14, following eleven days of steady rain, Sherman is ready to move again.

While on a personal reconnaissance, he spots a group of Confederate officers on Pine Mountain and orders one of his artillery batteries to open fire.

Lieutenant General Leonidas Polk, the "Fighting Bishop," is killed and Johnston withdraws his men from Pine Mountain, establishing a new line in an arc-shaped defensive position from Kennesaw Mountain to Little Kennesaw Mountain.