The Battle of Shiloh (Pittsburg Landing) April 6-7, 1862
 

Shiloh was perhaps the most important battle of the Civil War. The oh-so-close to successful Confederate attack was held and the Union counter-attack on the second day carried the day. It also put the North on the offensive in the West, where the Civil War was won, for almost the rest of the conflict.

Check it out here:

http://www.civilwarhome.com/shiloh.htm