Earth Prime—our Earth, upon which all the others are based.

Earth 12—Chronicles of the Republic.

Trigger event: September 11, 1991, terrorist attack response.

Catastrophic Event: an asteroid impact in the north-central Atlantic Basin between US and Europe.

Earth 1980—Littleton Chronicles.

Trigger event: April 24, 1980, Operation Eagle Claw. The military mission to rescue the hostages taken from the American Embassy in Tehran, Iran, was successful.

Earth 666—Chronicles of the Covenant.

Trigger Event: 2024 Election.

Catastrophic Event: World-wide Nuclear War