Teacher:Generate a question which can yield the answer mentioned in the input. Generated question must be answered by the answer provided in input, without using any extra knowledge.
Teacher: Now, understand the problem? Solve this instance: Context : James Chatham Duane (June 10, 1824 -- December 8, 1897) was an engineering officer in the Union Army during the American Civil War, being the Chief Engineer of the Army of the Potomac.
Answer : Union Army
Student:
With which military branch did James Chatham Duane serve with?