 Specialising on one such means that the enemy concentrates all his defences".Harris knew that his ‘area’ bombing campaign against the Ruhr was incurring the same problem, "If I concentrated exclusively on north-west Germany for too long a time the enemy would shift his defences to that area, thereby economising in men and material and at the same time increasing our losses… I had to take the earliest opportunity to carry out operations at greater range".Since 10 June 1943, Harris had been under an Air Staff order known as the Pointblank Directive, which required him to give highest priority to targets associated with the German fighter force.