The Union's primary goal at the Battle of Antietam was to defeat Lee decisively.

After a string of Confederate victories, Union commanders aimed to halt General Robert E. Lee's incursion into the North and inflict a major defeat on the Confederate Army. A significant triumph would not only elevate Northern morale but could also undermine Southern determination and sway international support. Accomplishing this objective was vital for the Union's strategy to regain control of the war and ultimately focused on preserving the Union.