Admiral David G. Farragut captured New Orleans and secured Union control of the Mississippi River delta in April of 1862. At this point, there was one remaining confederate stronghold. If General Ulysses S. Grant could continue to take control of the South, the capture of Vicksburg would split the Confederacy in half.
The Road to Gettysburg
Grant decided to march his troops South and around the city of Vicksburg, and then cross to the east side and attack from the south. To distract Confederate troops while doing so, Colonel Benjamin Grierson to tare railroads, burn depots, and fight skirmishes.
Fredericksburg and Chancellorsville
In May of 1863, Grant launched two attacks of Vicksburg, which failed. Grant decided that the only way to Capture Vicksburg was to put the city under siege. The siege lasted for 6 weeks, until July 4, 1863 when the Confederate commander at Vicksburg surrendered.
The Battle of Gettysburg
Shortly after the victory at Antietam, McClellan frustrated Lincoln because although he made great efforts at the Battle of Antietam, he let his efforts slip through and gave Lee chances to make a comeback. Lincoln wanted a general who was not scared of Lee’s reputation.
On December 13, 1862, General Burnside ordered a series of attacks in Fredericksburg, Virginia which gave the Union double as many casualties as the Confederacy. Following this battle came the Battle of Chancellorsville Virginia lead by General Hooker, which also failed leading Hooker to retreat.
Because of weakened Union forces, Lee decided to attack in the North. In June of 1863 he marched to Pennsylvania, raiding ts livestock, food, and clothing. After replacing General Hooker, Lincoln put General George Meade as commander in change who immediately headed North to intercept Lee. Then started the Battle of Gettysburg.