Over the last two hundred years, diplomatic interpreting has evolved quite significantly, due to changes in the world's geopolitical landscape, new political settings and technical revolutions which have vastly modified transportation and communications systems.
These are some salient phenomena:
The number of independent States has increased dramatically, particularly over the last century, and so have bilateral relations. At the same time, the international community which emerged with the establishment of the United Nations (1945) and its predecessor, the League of Nations (1919), continues to operate in multilateral settings.
If "war is merely the continuation of politics by other means", as Carl von Clausewitz said, one of the threads of the last two hundred years up until this day has been war and conflict, followed by peace negotiations.
Diplomatic relations have evolved from secret negotiations to a diplomacy by conference, and the roles of diplomats have become increasingly complex, not least because Heads of State are ever more often in direct contact with each other. At a time of instant communications, diplomats are still the main representatives of their nations abroad. Their movements, however, may be scrutinized from capitals and made public by the media almost in real time.
While French was generally considered as the primary language of diplomacy, at least in the Western hemisphere until the First World War, English has become in the last decades the main vehicle of global multinational conversation in the last decades.
None of the aforementioned developments translate into the end of language intermediaries. If anything, they are more necessary than ever, as a result of the proliferation of diplomatic interactions.
THE NINETEENTH CENTURY
When the main powers met at the Congress of Vienna in 1814 to reorganize the map of Europe, severely altered by the Napoleonic Wars, negotiators worked behind the scenes to preserve the interests of their respective nations. Ironically, the language which served as the main vehicle for the negotiations was French, that is, the language of the vanquished. Friedrich von Gentz, a Berliner in the service of Lord Robert Stewart Castlereagh (the United Kingdom of Great Britain and Ireland), and, at the same time, chief assistant to Prince Klemens von Metternich (Austria), is known to be the most eminent interpreter and translator at the forum, to whom historians attribute a significant role in the talks. Referring to his task at the Congress, where "translation was of far greater importance than interpreting", von Gentz laments in a diary entry, "What difficulties and misunderstandings might not be avoided, and how much time saved, by leaving matters trustfully in the translator's hands!"...