The invention of radar is 112 years old. A continuing interest has been and is being addressed in the long history of radar, with many old as well as recent publications. However, historical data on radar research and development are spread over many archives in the many nations where the independent and secret development of military radars almost simultaneously started in the 1930s, leaving important material still to be analyzed in both national and private archives. Moreover, unreliable and biased documents exist on this sensitive topic, calling for a wise usage of the written material. As a result of recent and careful archive research (and a result of some personal interviews), done by leading radar experts from four diff erent nations, this special section presents numerous interesting, less-known (in some cases, unknown) elements concerning the development of radar before and during the Second World War (WW II) in France, Ukraine (and former USSR), South Africa, and Hungary.@en

Within the frame of the Eurad-2014 Special Session ≪110 years of radar developments in Europe after Hülsmeyer's Telemobiloskop≫ this introductory paper contains (i) a retrospective analysis of the present literature and of its missing elements and (ii) a kind of presentation of this Special Session and its rationale.@en

It is a common belief by many people that the resonant-cavity magnetron was invented in February 1940 by Randall and Boot from Birmingham University. In reality, this is not the full story. Rather, it is a point of view mostly advocated by the winners of the Second World War, who gained a great benefit from this microwave power tube (thanks to a two-orders-of-magnitude increase of power) in the Battle of the Atlantic, in night bombing until the final collapse of the German Reich, and in many other operations. This paper discusses the contributions by other nations, mainly France, but also Germany, Japan, The Netherlands, the Czech Republic, the USSR, and even more, to the cavity magnetron and to its roots.@en