How does the author use foreshadowing in Behind Rebel Lines: The Incredible Story of Emma Edmonds, Civil War Spy?

Emma decided she would pose as a man and join the Army. When she stood in line at the recruiting station in Flint, Michigan, she feared she would be exposed as a woman. Fortunately, for her purposes, the Union Army was so desperate for able-bodied men that they had foregone the physical exam. This foreshadowed her recruitment into the Union Army.