The Do 217 was a direct successor to the Do 17 bomber, which was widely used by the Luftwaffe at the beginning of the war and was known by Allied pilots as the flying pencil.
Do 335 Pfeil was one of the fastest piston engine aircraft developed during World War II. Although the concept itself was older, the impetus for its completion was the deployment of fast British Mosquito aircraft and the deteriorating situation of Nazi Germany. The plane was to fulfill Hitler's vision of a fast bomber.
Do 335 Pfeil with tandem engines had no path to series production strewn with rose petals. However, its unusual design attracted the attention of the Leader himself, and in the end several dozen machines were produced.
Requirements for new German bombers of modern concept, which appeared in the form of He 111E-1, Ju 86D-1 and Do 17E-1 in February 1937 on the Spanish battlefield, arose in the first half of the 1930s. That is, at a time when Germany was still formally complying with the arms restrictions resulting from the Treaty of Versailles, imposed on the Weimar Republic by the victorious powers of 1919. The aircraft were therefore originally declared as civilian types; in reality, however, they were created in such a way that their construction could be used in both civilian and military roles without major problems.
The basic pillars of war, strategy and tactics, inevitably depend on an uncontrollable factor: the weather. With the increasing sophistication of weather collection, analysis, and forecasting in the early 20th century, weather forecasting became an integral part of World War II. For Europe, the Arctic was the most important geographic area for data collection, from where stormy weather moved east and south. Important data from Arctic stations, extending from Greenland to the Siberian Sea via Svalbard and Franz Josef Land, were almost completely cut off after these stations were gradually occupied by the Allies. The British went one step further and broadcast false weather data to Germany. Germany had to start acting aggressively to win the data collection war.