The served as a wake up call to union forces that the war was not going to be quick.

Confederate forces

Explanation:

On April 16, 1862 Confederate forces surprised some of the Union forces, who were at Shiloh Church outside Pittsburgh Landing, Tennessee, which was a small river town north of Corinth. Their attack, which would become known as the Battle of Shiloh, is considered one of the bloodiest battles to have ever taken place in North America. In some ways it served as a wake-up call to the Union since it indicated that this was not going to be a quick war, as they had initially thought.

your mothers brothers brother in law would be your father.