the Italians offered diplomatic, legal, and moral grounds for their actions against Ethiopia, the final justification for conquest was simply, and blatantly, that Italy was in urgent need of colonial expansion.
This “watery” strategic context to the Ethiopian crisis had its medial equivalent in the ideological struggles of the international airwaves. One of the major developments in international relations during the interwar period was the advent of national radio services designed for foreign listeners. While some cross-border reception of domestic programming was unavoidable among the densely packed nations of Europe, economic and political tensions encouraged the use of radio as an offensive instrument, with deliberate transmission across national frontiers increasingly employed as a central implement of ideological competition. As technological advances in transmission and reception made during the First World War were adapted to civilian use in the twenties, national and commercial radio services relied primarily on long and medium wave signals to broadcast within circumscribed geographical areas, offering programming that addressed national or regional audiences in much the same way that daily newspapers addressed and cultivated particular domestic readerships. Although the potential for international broadcasting had been recognized, radio in its first decade of widespread civilian use was mostly directed at national communities of listeners, and states and their broadcasting authorities asserted a monopoly of address within their jurisdictions, free of internal dissent and external critique. Whereas newspapers, books, and films were subject to customs regulation and seizure, and thus could be denied entry to one state from another, radio waves did not respect geopolitical borders. In their earliest manifestation, radio hostilities centered on frontier stations built along national cleavages in order to transmit to audiences straddling the demarcations between states. At times, these stations broadcast domestic programs that foreign listeners, by their proximity, could pick up; at others, they expressly broadcast to listeners across the frontier. Civilian radio service might have been new, but it was enfolded without difficulty into the fluctuating political equilibrium of the postwar world.
In their next phase of escalation, radio hostilities again centered on national frontiers, if from another, newer set of stations. In a widely cited article of the time, the American broadcaster César Saerchinger described this definitive step: “Since 1933 border warfare by radio has gone out of date, [and] this is not because the nations have abandoned the most modern of all weapons, but because the advent of the super-power station has made frontier stations superfluous.”8 As electrical phenomena, long and medium wave radio signals are disturbed by natural and artificial environmental features, such as mountain ranges, meteorological conditions, and infrastructure, which can markedly delimit the range of their effective reception. To mitigate interference, powerful transmitters were used to boost signals, although the cost of building such immense transmission facilities initially impeded the proliferation of high-powered stations. In the first half of the thirties, ideological and political considerations began to trump these economic constraints—Saerchinger notes that in 1930 there were no 100-kilowatt transmitters in operation, while seven years later there were seventy stations transmitting at this strength or higher. Here was an “arms race” measured in kilowatts, rather than ships or guns.9 These powerful transmitters covered huge territories, at once consolidating the ability of national services to monopolize their hold on domestic listeners while extending the capacity to address listeners far outside national boundaries. This contradiction was at the heart of radio hostilities, as transmitting power made it harder to maintain a clean distinction between domestic and foreign programming or to regulate the difference between national and international broadcasting services.
A final stage of interwar radio hostilities both confirmed and shifted their course: this was the rise of shortwave broadcasting, which “turned a European into a world problem.”10 Whereas all transmitters emit two kinds of signals, what are called “surface waves” and “sky waves,” long and medium wave broadcasts travel on the former, moving from the point of transmission to receivers on a straight line along a horizontal axis. Traveling on sky waves, shortwave transmissions reach the point of reception at a diagonal angle, after having ricocheted across great distances between earth and ionosphere and back to earth. With improvements to directional antennas, this property allowed engineers to aim shortwave programming at relatively specific areas around the world, but with far less transmitting power than was required for medium wave broadcasting: “The effectiveness of [directional] antennas is illustrated by the fact that a 5-kilowatt station with a highly directive antenna will put as strong a signal into England from the east coast of the United States as a 130-kilowatt station operating without directional antennas. Thus the analogy of waves undulating in widening concentric circles, used to describe long- and medium-wave transmission, should be replaced for short-wave transmission by one of ripples of radio energy that proceed outward and upward—in only one segment of the circle.”11 By the mid-thirties, long-range broadcasting had therefore become a feasible enterprise. Yet the potential of shortwave broadcasting was not solely realized by the great powers, as the technical requirements for shortwave transmissions allowed even the smallest, remotest, or poorest nations to broadcast to the world. Ethiopia was, in fact, a prime example of this new opportunity:
The Abyssinians’ little short-wave station near Addis Ababa—at an altitude of some nine thousand feet—operating on the ridiculously low power of one kilowatt, had made itself heard throughout the western world. Here was a romance of engineering, indeed. The Italians, who years ago built this station for the Abyssinians merely as a commercial telegraph terminus, little suspected that it would one day be used against them by their dusky enemies. It had no speech panel and no speech-input amplifier, though for some remote contingency there was an old-fashioned carbon microphone lying about. With this meagre equipment a Swedish engineer named Ernst Hammar, employed as director of communications by Emperor Haile Selassie, managed to rig up something that could actually make itself heard, first in London and then in New York.12
With cooperation from American networks, the station in Addis Ababa eventually became the source not only of Ethiopian broadcasts, but eventually of eyewitness reports from the nation by the Western press. This use of the station was one of the first instances of what quickly became a familiar wartime use of the medium. On a new scale, a “world” scale, radio waves could now be directed at specific groups of listeners.
While each of these phases of radio hostilities was distinct in its elaboration, the initiation of a “new” phase did not end or supersede the last, but instead represented an added dimension to the decade’s tensions as they were played out over the question of reaching listeners. A quick catalog of developments gives some indication of the additive nature of this escalation. Far from being outmoded, border stations remained especially potent in localized points of friction, many of which were located along the frontiers of Germany, from France to Austria to Czechoslovakia to Poland. Shortwave broadcasting enabled the establishment of empire broadcasting in France, the Netherlands, and the United Kingdom; the introduction of “diasporic” services from Italy, Japan, and Germany; and the opening of international airwaves to small nations such as the Irish Free State and Ethiopia. International broadcasters, such as the stations operated by the Vatican and the League of Nations, vied with the stridently internationalist programming of the Soviet Union, while the construction of mammoth medium wave transmitters capable of blanketing vast geographical areas created zones of ideological conflict conducted simultaneously through medium and shortwave transmissions. One of the most dramatic of these centered on the Mediterranean and Near East, where the Italians and British (and soon the Germans and French) jostled for influence in several languages. Indeed, the British Foreign Office requested that the BBC begin monitoring English-language news bulletins broadcast by foreign stations during the Ethiopian crisis, in order to gauge international opinion and keep abreast of developments that might affect diplomatic and strategic planning.13 In one of the first surveys of international political broadcasting, Thomas Grandin could already look back from 1938 at the role played by radio hostilities in the decade’s tumultuous course:
Our planet, potentially, has become an open forum, where a frank exchange of ideas could take place, on a scale never known
