For what is the battle of antietam best known?
a. it was the greatest union victory in the civil war
b. it was the greatest confederate victory in the civil war
c. it was the bloodiest battle of the civil war
d. it was the battle by which the south gained recognition in great britain

The Battle of Antietam is best known because c)it was the bloodiest battle of the Civil War. It totaled 22,717 losses ( as well as wounded and missing) and this is the two sides combined (both Confederate and Union soldiers). It was also the first major battle if the Civil War that took place on Union soil. The battle took place on September 17th, 1862.

A "treaty" is an agreed truce or temporary end of hostilities, since this takes place when two belligerents wish to stop fighting--either due to one side being defeated (or being close to defeat) or both sides viewing a cessation of hostilities as being favorable.