Trenchard was the single most important British officer in developing the policy of area bombing, claiming "an aeroplane is an offensive and not a defensive weapon” Even during the First World War, he had outfitted his planes with crude bomb dropping devices and sent them on raids into Germany, bombing a number of cities. The raid on Frankfurt, for example killed 120 civilians attending the opera.

Concerned about the cost of policing Churchill considered using poison gas. "I think”, he noted to Trenchard “you should certainly proceed with the experimental work on gas bombs, especially mustard gas, which would inflict punishment on recalcitrant natives without inflicting grave injury on them” Churchill knew well that even gas irritants could prove deadly to children, the elderly, and the infirm: "I am ready to authorise the construction of such [gas] bombs at once; the question of their use to be decided when the occasion arises."  There is some uncertainty about the use of gas at this time.