Armed with invisible ink, a cipher system, and a passion to end the war and preserve the Union, Elizabeth Van Lew became Butler'
s eyes and ears in the Confederate capital city. Truth be told, however, she became much more than that. She became a spymaster, the person responsible for running a network of agents, couriers, and safe houses that was very active during the war. In addition to the spying, Elizabeth Van Lew continued to maintain her Church Hill home as a safe house and something of a local Union spy headquarters. —The Dark Game, Paul Janeczko What is the central idea of this passage?
