The Area Bombing Directive (General Directive No.5 (S.46368/D.C.A.S)) was a 14 February 1942 British Air Ministry order directing RAF Bomber Command that "It has been decided that the primary objective of your operations should be focused on the morale of the enemy civil population and in particular the industrial workers". The directive listed a number of targets including the cities of Cologne, Duisburg, Düsseldorf, and Essen as priorites. The directive also stated that "You accordingly authorized to employ your forces without restriction" which lifted injunction placed on Bomber Command on 13 November 1941 ordering it to conserve its forces after the very heavy mauling it had suffered at the hands of Luftwaffe night fighters earlier that month.
The day after the directive was issued (on 15 February), the Chief of the Air Staff Charles Portal sought clarification from Air Vice Marshal Norman Bottomley who had drafted the previous days directive "ref the new bombing directive: I suppose it is clear the aiming points will be the built up areas, and not, for instance, the dockyards or aircraft factories where these are mentioned in Appendix A. This must be made quite clear if it is not already understood"
The first major target attacked in the campaign initiated by the directive was Essen on the night of March 8/March 9, 1942.. This was followed by repeated incendiary attacks on Essen and the other three large cities in the Ruhr Area, and then "as opportunity offered, fourteen other industrial cities in Northern, Central and Southern Germany."
Area Bombing Directive was modified by other directives issued by the Air Ministry. For example on 30 July 1942 (S.3319 A.C.A.S. Ops) gave priority to Transportation and Transformer Stations" for No Group and S.O.E. squadron. While on 4 September (S.46344 A.C.A.S. Ops) directed that incendiary bombs were to be "dropped in harvest season during normal bombing operations".The day before directive (S.46468/??? A.C.A.S. Ops) added the synthetic oil plant at Pölitz to the list of targets because the British believed it to be the largest in the world. On 14 January 1943 directive (S.46239/?? A.C.A.S. Ops) gave priority to attacking U-boat pens of Lorient, St Nazaire, Brest and La Pallice on the western French coast. In line with the bombing of Genoa and Turin on 23 October 1942 and a speech by the British Prime Minister Winston Churchill six days later, warning the Italian government that RAF would continue bombing Italian cities while Italy remained an Axis power, a directive was issued on 17 January 1943 (S.46368/??? A.C.A.S. Ops) added to the bombing list of targets the Industrial centres of Northern Italy — Milan, Turin, Gnoa, and Spezia.
Area Bombing Directive was superseded by the Casablanca directive (C.S. 16536 S.46368 A.C.A.S. Ops). It was approved by the Combined Chiefs of Staff at their 65th meeting on 21 January 1943 and issued by the British and United States Army Air Force Commanders on 4 February 1943. The primary objective was "The progressive destruction and dislocation of the German military, industrial and economic systems and the undermining of the morale of the German people to a point where their capacity for armed resistance is fatally weakened. Every opportunity to be taken to attack Germany by day to destroy objectives that are unsuitable for night attack, to sustain continuous pressure on German morale, to impose heavy losses on German day fighter force and to conserve German fighter force for the Russian and Mediterranean theatres of war" A list of target systems was also drawn up which gave priority to (a) Submarine construction yards, (b) German aircraft industry, (c) transportation, (d) oil plants (e) other targets in enemy war industry. The priority was to be varied with the strategic situation and the u-boat bases in France.
Marshal of the Royal Air Force Arthur Harris' view was stated when he in October 1943 urged the UK government to be honest to the public regarding the purpose of the bombing campaign and openly announce that: