Final answer:
The Battle of Antietam resulted in the issuance of the Emancipation Proclamation and ensured European powers would not recognize the Confederacy, which is a true statement of its impact.
Step-by-step explanation:
The statement that the Battle of Antietam was a major loss for the Confederacy because they also lost international support is True. While the battle itself did not result in a decisive Union victory, the aftermath was significant in terms of political strategy and international diplomacy. After the battle, President Lincoln felt confident enough to issue the Emancipation Proclamation, which had profound implications.
Although it did not immediately free all slaves, it effectively changed the nature of the Civil War from a battle over union to a battle for emancipation. This move, coupled with the bloodshed at Antietam, ultimately ensured that European nations would not recognize the Confederacy, as supporting a nation that was effectively fighting to preserve slavery became politically untenable.