Cylon Civil War

The Cylon Civil War is an internal conflict between humanoid Cylons.

One faction consists of the Number Ones, the Number Fours, the Number Fives, and the Number Eight copy known as Sharon Valerii, under the leadership of the Number One copy known as Cavil. The opposition consists of the Number Twos, the Number Sixes, and the majority of the Number Eights, under the leadership of the Number Six copy known as Natalie.

The seeds for the conflict were sown during the Battle of the Ionian Nebula, in which the Cylon Raiders break off the attack because one of them detects Samuel Anders as a humanoid Cylon. Cavil's faction votes to "reconfigure" (lobotomize) the Raiders so that they would continue the attacks on the Colonial fleet. Natalie's faction votes against this action, believing that the final five humanoid Cylons are present in the Colonial fleet. Her goal is to reunite all Cylon models, which also includes unboxing the Threes ("He That Believeth In Me", "Six of One").