Teacher:Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.
Teacher: Now, understand the problem? Solve this instance: Context: Mortimer Dormer Leggett (April 19, 1821 -- January 6, 1896) was a lawyer, school administrator, professor, and major general of the Union Army during the American Civil War.
Question: Which entity was Mortimer Dormer Leggett a part of?
Student:
union army