The North didn't want the Suuth to have Fort Sumter, so they went down to South Carolina to claim it back. But when Robert Andersen tried to negotiate with P. G. T. Beauregard, the Confederates fired at the Union ships, and they were forced to retreat.
Battle of Antietam September 17, 1862
The Union army, led by Irvin McDowell, attacked the Confederate army near Bull Run creek in Manassas, Virginia. The Confederates' defense was too strong, and the Union retreated.
Battle of Gettysburg July 1 - 3, 1863
Led by Albert Sidney Johnston, 30,000 Confederate soldiers attacked the unprepared Union army at a place they were staying at in Tenessee. More people died on the Union side, but they still didn't give up and it was a Union victory.
Battle of Chancellorsville April 30 - May 6, 1863
The Union performed a series of powerful assaults against the Confederate army, but like many other battles, the Confederates' defense was too good for the Union to win the battle. After a lot of fighting, both sides were too bloodied to continue and nobody won. This took place in Maryland.
General Lee began the second invasion of the North. Despite previous losses, the North held their defense and ended Lee's attempts. It resulted in the Gettysburg Address, which was a turning point in the purpose for the war.
The Union army had crossed onto General Lee's vulnerable flank in Virginia. Even though he was horribly outnumbered, he decided to stand and fight instead of retreat, and the Confederates ended up winning.