For precision attack emphasis was placed on the development of aircraft which could utilise the technique of dive bombing for which the Junkers Ju 87 "Stuka" was specifically designed. The Junkers Ju 88 was fitted with external dive brakes and a control system, similar to those of the Ju 87 and could carry out a dive bombing role, although it was primarily used as a level bomber. The light bomb loads carried by the Ju 87 had been used to great effect during the Battle of France. However, the Ju 87 was slow and possessed an inadequate degree of defensive weaponry, with only a single, 7.92mm calibre MG 15 machine gun at the rear of the cockpit for rearward defense. Furthermore, it could not be effectively protected by fighters, because of its low speed and the very low altitudes at which it ended its dive bomb attacks. The "Stuka" depended on air superiority, the very thing being contested over Britain. It was therefore withdrawn from attacks on Britain in August after prohibitive losses, leaving the "Luftwaffe" short of precision ground-attack aircraft.