sentences:  The British had been waiting for the opportunity to experiment with an incendiary-intensive raid, considering it a kind of retaliation for the German raid on Coventry.This was the start of a British drift away from precision attacks on military targets and towards area bombing attacks on whole cities.In his 1974 book "The Ultra Secret", Group Captain F. W. Winterbotham asserted that the British government had advance warning of the attack from "Ultra"