Infiltrating and undermining an empire

A wonderful book by Eric Frank Russel - in 1957 - Wasp

Shows how one man, transformed and disguised as the fascistic enemy, uses guerilla tactics to stir up trouble from within.

Any other books that explore this theme in a sci-fi setting?

Timothy Zahn explores guerrila warfare using two different augmented sets of troops:

  • The Blackcollar and its sequels looks at biological augmentation
  • the Cobra series looks at mechanical implant and was an extension of his short story, “When Johnny Comes Marching Home”