[3] When the Second World War began in 1939, US President Franklin D. Roosevelt issued a request to the major belligerents to confine their air raids to military targets.

[4] The French and the British agreed to abide by the request "upon the understanding that these same rules of warfare will be scrupulously observed by all of their opponents".

[6] The policy was abandoned on 15 May 1940, two days after the German air attack on Rotterdam, when the Royal Air Force was given permission to attack targets in the Ruhr, including oil plants and other civilian industrial targets that aided the German war effort, such as blast furnaces that at night were self-illuminating.

[8] The Jules Verne, a variant of the Farman F.220 of the French Naval Aviation, was the first Allied bomber to raid Berlin.

[11] Before 1941, Berlin, at 950 kilometres (590 mi) from London, was at the extreme range attainable by the British bombers then available to the Allied forces.

It could be bombed only at night in summer when the days were longer and skies clear – which increased the risk to Allied bombers.

[citation needed] At the start of hostilities, the saying "if a single enemy bomber appears over Berlin, I will be called Meier" made the rounds as attributed to Göring.

[14] When air raid sirens in Berlin sounded increasingly frequent after 25 August 1940, they swiftly became known as Meiers Waldhörner (lit.

'Meier's Bugles') in the Berlin vernacular, additionally apt because not only was Göring known for living large with a love for castles and leather uniforms, he was also the leader of the German Hunting Society.

The head of the Air Staff of the RAF, Charles Portal, justified these raids by saying that to "get four million people out of bed and into the shelters" was worth the losses involved.

[16][17] The Soviet Union started a bombing campaign [ru] on Berlin on 8 August 1941 that extended into early September.

[18] Heavy Army bombers, operating from near Leningrad, executed one raid to Berlin on 11 August, with only few machines reaching the target.

[21] This failure led to the dismissal of Peirse and his replacement (in February 1942) by Arthur Travers Harris, who believed in both the efficacy and necessity of area bombing.

They sowed the wind, and now they are going to reap the whirlwind.At the same time, new bombers with longer ranges were coming into service, particularly the Avro Lancaster, which became available in large numbers during 1942.

During most of 1942, however, Bomber Command's priority was attacking Germany's U-boat ports as part of Britain's effort to win the Battle of the Atlantic.

A prelude to the 1943 raids came from De Havilland Mosquitos, which hit the capital on 30 January 1943, the tenth anniversary of the Nazis' Machtergreifung.

The raid caused extensive damage to the residential areas west of the centre, Tiergarten and Charlottenburg, Schöneberg and Spandau.

Several other buildings of note were either damaged or destroyed, including the British, French, Italian and Japanese embassies, Charlottenburg Palace and Berlin Zoo, as were the Ministry of Munitions, the Waffen SS Administrative College, the barracks of the Imperial Guard at Spandau and several arms factories.

By this time cumulative effect of the bombing campaign had made more than a quarter of Berlin's total living accommodation unusable.

[27] There was another major raid on 28–29 January 1944, when Berlin's western and southern districts were hit in the most concentrated attack of this period.

On 15–16 February, important war industries were hit, including the large Siemensstadt area, with the centre and south-western districts sustaining most of the damage.

During December and January regular raids killed hundreds of people each night and rendered between 20,000 and 80,000 homeless each time.

[34] In 1943, the United States Army and the Standard Oil company built a set of replicas in western Utah of typical German working class housing estates, "German Village", which would be of key importance in acquiring the know-how and experience necessary to carry out the firebombings on Berlin.

[35] The Big Week (Sunday, 20–Friday, 25 February 1944) heavy bomber offensive began shortly after the Eighth Air Force commander, Maj. Gen. Jimmy Doolittle, had implemented a major change in fighter defense of USAAF strategic bomber formations that had bolstered the confidence of U.S. strategic bombing crews.

In 1945, the Eighth Air Force launched a number of very large daytime raids on Berlin, the last of them being on 18 March (there were bombing raids to Falkensee and Spandau, near Berlin, on 28 March),[39] the 15th Air Force launched its only bombing mission to Berlin on 24 March,[39] and for 36 nights in succession scores of RAF Mosquitos bombed the German capital, ending on the night of 20/21 April 1945 just before the Soviets entered the city.

[43][44] In the raid, led by Lieutenant-Colonel Robert Rosenthal of the 100th Bombardment Group flying in an H2X-equipped pathfinder B-17G Fortress s/n 44-8379[relevant?]

The area that suffered the greatest damage did not include railway main lines, which were more northern (Stadtbahn) and southern (Ringbahn).

The bombing was so dense that it caused a city fire spreading eastwards, driven by the wind, over the south of Friedrichstadt and the northwest of neighboured Luisenstadt.

In the last days of the war the Red Air Force also bombed Berlin, also using Ilyushin Il-2 and similar aircraft for low-level attacks from 28 March onwards.

The Flak guns were increasingly manned by the teenagers of the Hitler Youth as older men were drafted to the front.