But Elizabeth wanted to do more than simply minister and comfort the wounded. A Unionist, believing in "one nation . . . Indivis
ible," she needed to do more. When she learned of Virginia's secession from the Union in 1861, she felt, in the words of one historian, "profoundly betrayed." She believed that the secessionists did not represent the majority of the citizens of Virginia. She was compelled to act in any way she could to help repair a nation torn apart. How does this excerpt develop the central idea that espionage during the Civil War was often carried out by untrained citizens? It enhances the reader's understanding by explaining why training was unnecessary. It changes the reader's perception of what information a spy was able to obtain. It explains an ordinary person's motivation for conducting espionage against the enemy. It adds moral complexity to espionage, due to the use of secret and dangerous methods.
You have to make sure your claim is relevant to the rest of the essay, or why even mention it. The thesis is supposed to over view what the whole essay will be about.