You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.
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Question: Category: TO PROTECT 
Clue: This "service" is best known for protecting the president, but also investigates forgery

Answer: the secret service


Question: Category: THE WRITE BROTHERS 
Clue: The younger brother of novelist Heinrich Mann, he wrote "Joseph and His Brothers"

Answer: thomas mann


Question: Category: A STATE OF CIVIL WAR 
Clue: On September 17, 1862 Gen. Robert E. Lee's Northern march was halted in this slave-holding Union state

Answer:
maryland