The dominance of the Royal Navy's surface fleet prevented the German units returning to ports in the Baltic Sea or Germany.

The surviving ships, the battleships Scharnhorst and Gneisenau and the cruiser Prinz Eugen, docked in the port of Brest, France.

The proximity of the ports to Royal Air Force (RAF) airfields allowed a large number of sorties to be flown against the targets in quick succession.

Oberkommando der Marine (the Naval High Command), and Adolf Hitler desired to move the ships out of range of potential air raids.

In December 1941, Oberkommando der Luftwaffe (High Command of the Air Force) was ordered to plan an operation to protect the three German capital ships to escape from Brest to Germany through the English Channel.

Whilst in port, the ships were in easy range of British air power and suffered frequent attacks and some damage.

Night bombing was safer as the Germans lacked night-fighters and the 18 losses to enemy action were claimed by anti-aircraft guns.

[4] Concerned after the loss of Bismarck, Adolf Hitler ordered the Kriegsmarine to move the ships to Germany for overhauls in preparation for their deployment to Norway.

After lengthy discussions the Oberkommando der Marine opted for the shorter but arguably more dangerous route, through the English Channel.

During the meeting Jeschonnek stood his ground against Galland and refused to guarantee reinforcements to the Western fighter forces from other theatres.

The existence of the operation was so secret that both Jeschonnek and Galland had to sign secrecy pledges as they left Hitler's Headquarters in East Prussia.

[4] The details of the plan were worked out with Oberst (Colonel) Karl Koller, the chief of staff of Luftflotte 3 (Air Fleet 3, Generalfeldmarschall Hugo Sperrle).

[8] To assemble sufficient strength some training units had to be mobilized (the bulk of the Jagdwaffe was in the Soviet Union owing to Operation Barbarossa).

They created a subtle jamming technique which increased atmospheric interference which degraded the performance of British coastal radars.

Dornier Do 217s of Kampfgeschwader 2 (Bomber Wing 2) was ordered to fly electronic deception missions over the western channel to divert enemy aircraft.

Fliegerkorps IX ( Joachim Coeler) prepared to strike at RAF bases in south-western England and to engage and slow down British naval forces that might attempt an interception.

Dening sent a message to First Sea Lord Dudley Pound: The short cut of the German ships is via the English Channel.

Taking all factors into consideration, it appears that the Germans can pass east up the Channel with much less risk than they will incur if they attempt an ocean passage.

[12]Air Marshal Philip Joubert de la Ferté, commander-in-chief of RAF Coastal Command agreed this was the probable route.

Kampfgeschwader 2 operated in a support role, mainly maritime interdiction and air raids on enemy airfields in southern England, to distract the RAF from the Channel.

The Second, "Line SE" watched due north of the port and the third, "Habo", covered the area between Le Havre and Boulogne.

The mist was threatening to deny a clear landing run for the Hudson, so it was recalled an hour early, just as the German ships were approaching "Habo".

By chance, a mechanic on the radar station at Fairlight, East Sussex had just finished repairing the equipment when he picked up 27 echoes at 10:15 on 12 February, south of Cap Gris Nez.

The performance of the radar was suppressed because of jamming measures (Ballstöranlage) undertaken by two Heinkel He 111s which had been flying off the south coast from their airfield near Paris.

[23] Galland ordered all low flying to cease and allowed Max Ibel and his team aboard Scharnhorst to break radio silence.

Of the 242 bombers that took part in the missions, it is likely only 39 conducted attacks, with a possible that a 16, suggesting a total of 54 aircraft released bombs against the ships, of which 15 were shot down.

RAF Fighter Command also threw in fighter-bombers to try and inflict damage, operating Hawker Hurricanes over the Dover area.

Confusion owing to the weather and the lack of central control of British sea and air forces caused each element to work independently.

[45] Production and procurement remained in favour of Bomber Command, producing types for the strategic bombing campaign over Germany, even after the failure of Fuller.

[46] Donnerkeil was a watershed in electronic warfare, by jamming, Martini removed British inhibitions concerning the use of ECM against the Kammhuber line on the Continent and paved the way for the debut of Window (Chaff) in June 1943, which had a devastating effect on the ability of German night-fighter radar defences to locate and intercept RAF bombers during the Defence of the Reich.