The year opened poorly for the Northern military. In the West, their efforts to capture Vicksburg during the winter and spring were continually frustrated. In the East, the Union forces were defeated at Chancellorsville in early May. The North rebounded in June and July with a trio of successes: the Tullahoma campaign, which cleared major Confederate forces from Tennessee; the capture of Vicksburg, which together with the fall of Port Hudson, Louisiana, gave the North control of the Mississippi River; and the Battle of Gettysburg, where Lee's last movement across the Potomac River ended in bloody repulse. Another success at Chattanooga in late November closed a most auspicous year of campaigning for the North. The Union also adopted a national conscription act in 1863, prompting wide opposition and considerable violence. The Emancipation Proclamation went into effect on January 1, and soon thereafter the North began recruiting black soldiers on a large scale. Shortages of food and material goods became quite severe in the Confederacy, which experienced bread riots at several locations.

B. Beginning of the Vicksburg Campaign

In December 1862 Grant began to gather troops for a campaign directed at opening the Mississippi River to the Union and dividing the Confederacy in two. The key to the Confederate defenses was Vicksburg, the heavily fortified Mississippi city that commanded the river from its high bluffs. Grant first planned to march south from Memphis, Tennessee, while another army under William Tecumseh Sherman proceeded by water to Chickasaw Bluffs, just north of Vicksburg. Grant's advance was stopped on December 20, when Confederate General Earl Van Dorn cut in behind him and destroyed Grant's supply base at Holly Springs, Mississippi. Sherman's advance continued, but a week later he was repulsed with heavy losses at the Battle of Chickasaw Bluffs. His report was short but accurate: ""I reached Vicksburg at the time appointed, landed, assaulted, and failed.""

Before crossing the river, Grant had sent the federal cavalry commander Benjamin H. Grierson on a daring raid that Grant hoped would divert the attention of the Confederates from his own operations. Grierson and 1700 men left La Grange, Tennessee, on April 17, 1863. Sixteen days later, after covering 966 km (600 mi), he reached Baton Rouge, Louisiana. He had destroyed miles of railroad, taken 500 prisoners, and eluded thousands of Confederate troops sent against him. He achieved this great feat with the loss of only 24 men.

C. Chancellorsville

At the same time that the western army was poised on the banks of the Mississippi, the Union Army of the Potomac and the Confederate Army of Northern Virginia were locked in battle. Hooker had spent three months strengthening the Army of the Potomac, restoring discipline, and building up supplies. When the warm winds of spring dried the roads, he had 134,000 well-equipped men ready for duty. In late April, leaving part of his army outside Fredericksburg, he moved 70,000 troops across the Rappahannock as a first step in a drive on Richmond. Lee, learning that Hooker had divided his force, also left part of his army in Fredericksburg. He sent another part under Stonewall Jackson against Hooker's right wing. On May 2, 1863, Jackson hit with such force that Hooker's whole line was driven back. The next day, Lee attacked Hooker's center with the remainder of the army. Hooker had reserves waiting to be called in, but he had been stunned by a shell that had struck headquarters and was unable to give the necessary orders. His line gave way. On May 5 Hooker retreated north of the Rappahannock. The Army of the Potomac had again failed to reach Richmond.

Union casualties at the Battle of Chancellorsville were 17,300 against 12,750 Confederate casualties. However, the Union percentage lost was much lower, and Lee and his army suffered grievously because of the death of Stonewall Jackson, Lee's ablest subordinate.

D. Fall of Vicksburg

In the west Grant turned to new land and water tactics in cooperation with the Union river fleet commanded by Admiral David D. Porter. From January through March 1863, four attempts were made to bypass Vicksburg by cutting canals or changing the course of rivers. All failed.

In April Grant put his final plan into operation. He would march his army down the west side of the Mississippi to a point below Vicksburg. Porter's gunboats and barges would run past the Confederate artillery on the river, thus supplying the army and furnishing transports for ferrying the men to the east side of the river. The army would then march into Mississippi behind Vicksburg. It would either defeat the Confederates in open battle or drive them into the river stronghold, where they would be forced to surrender sooner or later. On the night of April 16, 1863, Porter ran through the fire from the shore batteries and lost only 1 of his 12 boats. A few nights later, 6 transports and 13 barges tried the same feat, and 5 transports and 6 barges came through. In spite of the losses, Grant had enough supplies and shipping to proceed with his plan.