The 'Hardest Day' of the Battle of Britain

18 August, which had the greatest number of casualties to both sides, has been dubbed "The Hardest Day". Following the grinding battles of 18 August, exhaustion and the weather reduced operations for most of a week, allowing the Luftwaffe to review their performance. "The Hardest Day" had sounded the end for the Ju 87 in the campaign. This veteran of Blitzkrieg was too vulnerable to fighters to operate over Britain, and to preserve the Stuka force, Göring withdrew them from the fighting. This removed the main Luftwaffe precision-bombing weapon and shifted the burden of pinpoint attacks on the already-stretched Erpro 210. The Bf 110 had also proven too clumsy for dogfighting with single-engined fighters, and its participation was scaled back. It would only be used when range required it or when sufficient single-engined escort could not be provided for the bombers.

The losses of Junkers 87 "Stuka" dive bombers during the day were so severe that this type of aircraft was withdrawn from the main battle by the Germans, apart from a few later isolated sorties. It has been asserted that 18 August was the "hardest day" of the Battle of Britain. However, the intensity of air activity was greater on 15 and 16 August and the number of Fighter Command aircraft in combat was exceeded on at least half a dozen other days.