Monoid revolution
The Monoid revolution was a war that occurred onboard the Ark in the 57th Segment of Time, some point after the First Doctor, Steven Taylor, and Dodo Chaplet had caused and cured a plague of the common cold. It enabled the Monoids to wrest control of the Ark from the Guardians.
In the struggle for position of leader, One XVII's forebear, Monoid One I, emerged from the ranks of the Monoids after he had "seen off" all opposition, then uniting into the Monoid Order against the Guardians.
Although some Monoids had wanted to win the battle and then strike up an alliance with some of the Guardians, Monoid One the First quickly denounced this as treachery. Those who had proposed the plan were condemned and executed, as any weakening of resolve at that point might have let the Guardians insinuate their way back into power. (PROSE: The Ark)