When Enzo G. Castellari finished the film
Kill Them All and Come Back Alone, he asked the producers what their next film would be. They replied a war epic about the
Battle of Britain with the
Harry Saltzman version yet to be released. Enzo thought that was a great idea but the producers had their sights on
Alberto De Martino directing. The producers stipulated that stock footage of the actual Battle of Britain needed to be used in the film and that it should be used in a
split-screen method. They asked Enzo if he would direct the special effects sequences and cut it with the stock footage using a split-screen method. Enzo had never heard of "split screen" so he was shown the American films
The Thomas Crown Affair and
The Boston Strangler. He shot the effects sequences and mixed it using a triple split screen method. An example is having a British plane shoot on the left side, having a German plane being hit on the right side, and having stock footage in the middle. When shown this split-screen footage, the producers were so impressed they decided to have Enzo direct the entire picture. After this, Enzo sat down with a writing partner for a week to rewrite the overlong script to make it more action-oriented and less of a "soap opera". The film is entirely fictional and historically inaccurate. For instance, the RAF never shot down 94 German planes in a single day; London was never "blitzed" in one sortie by "1,000 planes"; and the RAF Control Centre was never attacked in any way. Actually, the Air Ministry building (Adastral House) was badly damaged by a bomb. 46 people were killed and at least 200 others suffered serious injuries with five members of the Women's Auxiliary Air Force (WAAF) killed on the upper floors of the Air Ministry). The director uses
Messerschmitt Bf 109s (or near-replicas of them) as RAF "
Hawker Hurricanes", and
Supermarine Spitfires as Luftwaffe "Bf 109s". The fictional "bombers" that are supposed to be
Heinkel He 111 are in reality
CASA 2.111 similar planes built in Spain under licence. ==Releases==