''If he blows his cover he might blow the lid
  So he stays in the shadows like he always did...''

Published January 17, 1944- "This information is to characterize simple sabotage, to outline its possible effects, and to present suggestions for inciting and executing it...''

Simple Sabotage Field Manual (Office Of Strategic Services,1944)

https://archive.org/details/SimpleSabotageFieldManualStrategicServicesProvisional