The Enemy Within Campaign is a campaign for Warhammer Fantasy Roleplay (1st Edition), published by Games Workshop between 1986 and 1989.
Its theme is one of treachery, with hidden powers of Chaos plotting the downfall of the Empire. The original material was a big success with fans, being voted the Best RPG Campaign of all time by the French RPG Magazine Casus Belli.
The campaign comprised six adventures:
- The Enemy Within (introductory adventure with extensive source material for the Empire)
- Shadows Over Bögenhafen
- Death on the Reik
- Power Behind the Throne
- Something Rotten in Kislev
- Empire in Flames
The Warhammer City Middenheim sourcebook ties in closely with Power Behind the Throne but is not part of the campaign.
Games Workshop later republished parts of the campaign in consolidated editions:
When Hogshead Publishing re-printed the campaign in the early 1990s, they incorporated the content of The Enemy Within into Shadows Over Bögenhafen. The Hogshead edition of Power Behind the Throne also includes an additional short adventure that was designed to ease the transition from Death on the Reik.
James Wallis of Hogshead Publishing intended to re-design the final part of the campaign from the ground up, titling it Empire in Chaos. Sadly, this last book was never published (see the entry for Empire in Flames for more details).
Fan-published campaign materials include an alternate rewrite of Empire in Flames, The Empire at War, and The Enemy Within: A Companion, which provides GM advice, suggestions, and alternate handouts for the entire series.
A revised "Director's Cut" of the campaign for Warhammer Fantasy Roleplay (4th edition) began release in 2019.