Worlds of the Imperium

by Keith Laumer

"Worlds of the Imperium" by Keith Laumer is a science fiction novel published in 1961. When American diplomat Brion Bayard is kidnapped by agents from a parallel universe, he discovers a world where the American Revolution never happened and the British Empire unified most of civilization. Bayard must impersonate his dictator counterpart from another timeline to stop devastating raids—but nothing goes according to plan when he meets his double and uncovers a conspiracy that threatens multiple realities.