After the declaration of war on Nazi Germany by Britain and France in the aftermath of the German invasion of Poland, nine months of stalemate took place along the Western Front.

The British Expeditionary Force escaped encirclement during the Battle of Dunkirk, but the Wehrmacht captured Paris on 14 June and overran half of France.

The Luftwaffe was to eliminate enemy air power and the Kriegsmarine was ordered to make all the necessary preparations for transporting the German army (Heer) across the English Channel.

[16] If this proved not to be the case, the Luftwaffe would then support the army and prevent the Royal Navy interdicting German sea traffic.

Nevertheless, in the belief they were having considerable effect on Fighter Command, they prepared to launch their all-out assault on the RAF the following day.

The breaking of the Enigma machine and poor Luftwaffe signals discipline allowed the British easy access to German communications traffic.

Whatever the truth, Ultra, and the Y service in particular, gave the British an increasingly accurate picture of German order of battle deployments.

[30] Joseph "Beppo" Schmid was commander of the Luftwaffe's Military Intelligence Branch (Abteilung 5 as Chief IC).

In his list of omissions, Schmid failed to mention the RAF maintenance and organisation operations, which put back damaged aircraft with rapid effect.

[31][32][33] The lack of sustained and concentrated attacks on radar left it free to help direct the deployment of RAF units at opportune moments.

[34] The following targets were chosen for attack on 13 August 1940: The keystone of the British defence was the complex infrastructure of detection, command, and control that ran the battle.

[64] The core of Dowding's system was implemented by Dowding himself: the use of Radio Direction Finding (RDF or radar) was at his behest, and its use, supplemented by information by the Royal Observer Corps (ROC), combined with an organisation system to process the information was crucial to the RAF's ability to efficiently intercept incoming enemy aircraft.

The technology was named RDF with misleading intent – the vague description would disguise the full nature of the system to the enemy if its existence ever became known.

[65][66] The first indications of incoming air raids were received by the Chain Home Radio Direction Finding (RDF) facilities, which were located along the coastlines of Britain.

The information from RDF and the Observer Corps were sent through to the main operations room of Fighter Command Headquarters at RAF Bentley Priory.

[69] Colour-coded counters representing each raid were placed on a large table, which had a map of Britain overlaid and squared off with a British Modified Grid.

Because Group had tactical control of the battle, the operations room was different in layout from the main headquarters at Bentley Priory.

Extensive radio and telephone equipment transmitted and received a constant flow of information from the various sector airfields as well as the Observer Corps, AA Command and the navy.

[1] For an hour after dawn on 13 August, there were few German tracks upon the plot tables in operations rooms, and none at all in the central and eastern Channel.

[71] Owing to the mistake by the Observer Corps, and the Geschwader being missed approaching the eastern, instead of central Channel by radar, KG 2 hit the RAF airfield.

For some time afterward, this wrong claim convinced German intelligence that Eastchurch was a fighter station and the Luftwaffe would launch seven fruitless raids on it in the coming weeks.

[54] Most units of Luftflotte 2 received the order to abandon morning operations, but some began their attacks aimed at airfields and ports in southern Britain.

[83] ZG 2 was supposed to provide escort during one these attacks, and in a breakdown of communications, arrived over the target without their Ju 88s, which had been ordered to stand down.

I./JG 53 flew a fighter sweep ahead of the bombers from Poole to Lyme Regis in order to tempt the RAF into battle.

[103] Another group, led by Gruppenkommandeur Hauptmann (Captain) Friedrich Achenbrenner, dispatched 15 He 111s from bases in Brittany across the Irish Sea to strike at the Short Brothers factory at Queen's Island, Belfast Northern Ireland.

Other bombers, commencing the night stage of Adlertag, resolutely flew the length and breadth of Great Britain, bombing Bristol, Cardiff, Swansea, Liverpool, Sheffield, Norwich, Edinburgh and Aberdeen.

The Germans may have reasoned that if bases such as Manston, Hawkinge and Lympne were neutralised through the attacks on 12 August, then Fighter Command may have had to move onto these airfields.

During the Battle of Britain (and, indeed, the rest of the Second World War), both sides claimed to have shot down and destroyed more enemy aircraft on the ground and in the air than they had in reality.

[111][112] To the contrary, OKL believed that the radar stations would benefit the German effort by sending RAF forces into large-scale air battles for the Luftwaffe to decimate.

[Notes 2] Having failed to defeat the RAF, the Luftwaffe adopted a different and clearer strategy of strategic bombing known as The Blitz.