Union general William T. Sherman believed newspaper correspondents to be liabilities. “A spy is one who furnishes an enemy with knowledge useful to him and dangerous to us,” Sherman wrote in an 1863 letter. “I say—in giving intelligence to the enemy, in sowing discord and discontent in an army—these men fulfill all the conditions of spies.”

In ancient Indian espionage networks, a sattri was an orphan-spy trained from youth in palmistry, magic, omens, and augury. 

Charles d’Éon de Beaumont went to Russia in 1755 as a secret correspondent of French king Louis XV. Disguised as a woman, he obtained an appointment as reader to a Romanov empress; he returned for a mission the next year dressed as a man. By the 1770s speculation about his gender reached such fervor that odds were quoted by London brokers. An 1810 postmortem finally confirmed that he was anatomically male; Marie Cole, his companion of fourteen years, reportedly “did not recover from the shock for many hours.”