21.   During the Vietnam era, they evolved into special forces units, trained to operate behind enemy lines, collect intelligence and carry out assassinations.

22.   He fought at Stalingrad, on the Don River front and in Ukraine, and frequently parachuted behind enemy lines.

23.   He headed a mobile leaflet unit as art director, poster designer and political cartoonist for publications air-dropped behind enemy lines.

24.   He was parachuted behind enemy lines in Europe.

25.   He was wounded in the North African desert, and he won a Silver Star for a reconnaissance mission he led behind enemy lines.

26.   He was found in a foxhole two weeks later, delirious with pneumonia, unable to tell anyone how he had managed to survive behind enemy lines.

27.   He was missing in action behind enemy lines for three weeks and presumed dead, but found his way back to his unit.

28.   He was sent behind enemy lines, working with Chinese guerrillas in the vicinity of Hong Kong.

29.   His was hardly a cloak-and-dagger operation with hard-to-remember codes, double identities and safe houses behind enemy lines.

30.   In the Civil War, women provided casualty care and spied behind enemy lines.