Respuesta :
The author develops the central idea during the Civil War still involved fieldwork by including more detailed information about who did fieldwork for the Union and how it was done.
The correct answer is "by including more detailed information about who did fieldwork for the Union and how it was done".
Espionage was a practice which was greatly used during the Civil War. The author focuses on the terms "scouts" and "spies". Armie would normally encounter outsiders who approached them. Some of them identified themselves as scouts coming from other regiments. However, if they were not to be believed, they were subsequently executed under the presumption they were "spies". On the other hand, some spies actually got away with it and ended infiltrating enemy ranks. After a couple of weeks with the enemy, they would escape and return to their squads with valuable information.