When the Lawgiver, who moderated the actions of the Engineers and Uncreators, was dying, the Engineer Prime went to Earth in 1930 to find a new one. Neither an Engineer or Uncreator could be the replacement, as then the new one would be biassed towards those it had come from. When Peter Rathbone demanded the Triskele surrender to him and they did not immediately agree, he shot and killed the Lawgiver, possibly psychically manipulated into doing so by the Uncreator Prime.
This freed the Uncreators, who turned more bestial from centuries of suppressed rage. Before they could cause severe damage, Lord Tamworth fought and defeated the Uncreator Prime. Trying to mentally influence Rathbone to kill Tamworth, Peter was able to gain enough control to shoot the Uncreator Prime instead.