The Battle of Antietam significantly increased support for Lincoln leading into the 1862 elections.

Despite the battle's heavy casualties, it was viewed as a strategic victory for the Union, allowing Lincoln to issue the Emancipation Proclamation shortly thereafter. This proclamation not only redefined the war’s purpose but also galvanized public support for the Union cause, attracting more enlistments. As a result, voters were more inclined to support Lincoln and the Republican Party, viewing them as committed to preserving the Union and advancing the fight against slavery.