The romance of war in its most thrilling form is exemplified in this narrative of the adventures of "The World's Greatest Military Spies and Secret Service Agents." Much has been published upon the subject of espionage, and the memoirs and secret histories of the courts of Europe give us instances of men and women who have gained favor and money, if not honor and glory, by selling back-stairs gossip concerning their fellow creatures; but the aim of the present work has been rather to relate the big exploits of those who faced great personal danger and risked their lives for the sake of flag and country.