ANNEX (Reference paragraph 7 of the report) Method of Attack 1. In face of the ground and air defences of this country, the G.A.F. could not spray gas even from the maximum height of 15,000 feet without suffering crippling losses of aircraft, since this method of gas attack, if it is to be effective, involves flying either to and fro over the target or in formation on a straight and level course. Any gas attack would, therefore, almost certainly be made with gas bombs. The Germans are known to have gas bombs of 12, 50 and 250 Kg., while bombs of 500 and 1,000 Kg.