Given the task definition, example input & output, solve the new input case.
Given a passage and a question, find the answer to the question based on the passage. The answer should consist of only one word that lies in the span of only one of the sentences in the passage.
Example: Paragraph: Nix v. Hedden , 149 U.S. 304 ( 1893 ) , was a decision by the Supreme Court of the United States that , under U.S. customs regulations , the tomato should be classified as a vegetable rather than a fruit . The Court 's unanimous opinion held that the Tariff Act of 1883 used the ordinary meaning of the words `` fruit '' and `` vegetable , '' instead of the technical botanical meaning .
Question: is tomato a fruit or vegetable us supreme court

Output: vegetable
The answer 'vegetable' is correct as it lies in the sentence - "Nix v. Hedden , 149 U.S. 304 ( 1893 ) , was a decision by the Supreme Court of the United States that , under U.S. customs regulations , the tomato should be classified as a vegetable rather than a fruit ", which is a part of the passage.

New input case for you: Paragraph: McClellan had halted Lee 's invasion of Maryland , but Lee was able to withdraw his army back to Virginia without interference from the cautious McClellan . McClellan 's refusal to pursue Lee 's army led to his removal from command by President Abraham Lincoln in November . Although the battle was tactically inconclusive , the Confederate troops had withdrawn first from the battlefield , making it a Union strategic victory . It was a sufficiently significant victory to give Lincoln the confidence to announce his Emancipation Proclamation , which discouraged the British and French governments from pursuing any potential plans to recognize the Confederacy .
Question: who won the civil war battle of antietam

Output:
Union