Briefing - The Origins of International Peacekeeping Operations
Military forces of many nations have often undertaken "military operations other than war," such as disaster relief or punitive expeditions, but the notion of "peacekeeping" operations is a relatively rare one. The earliest example of a peacekeeping mission seems to have been in 1625, during a lull in the Thirty Years' War. In 1624 the Count of Savoy, a French ally, had gone to war with the Republic of Genoa, a Spanish ally, over the ownership of some villages that dominated certain mountain passes of some strategic importance. It was a desultory war, but the "superpower" allies of the two small states, France and Spain, were concerned that it might ultimately involve them at a time when both were otherwise occupied. They intervened and pressured the two sides to agree to a cease fire and mutual withdrawal from the disputed areas, which were then policed by troops borrowed from the Pope. The peace was kept for about two years, when the French and Spanish decided to have it out themselves.
This early example of international intervention in the name of peace displays substantially the same pattern that most peacekeeping operations followed during the Cold War; The convergence of the interests of the superpowers - in this case France and Spain - to avoid becoming embroiled in a local war caused them to establish and enforce the peace.
In the wake of the Napoleonic Wars, the conservative powers of the "Concert of Europe" - Austria, France, Prussia, and Russia - several times mobilized substantial forces to intervene in internal crises in the weaker powers, primarily to suppress liberalism. Thus in 1821 a French Army intervened in Spain, while an Austrian one entered Naples, in order to overthrow liberal governments, while Prussian, Austrian, and Russian troops intervened in the Duchy of Warsaw in 1831 to surpass a Polish nationalist outbreak, and later in the century the major European powers several times provided troops to implement agreements between the Ottoman Empire and various minor Balkan powers.
Although arguably the "China Relief Expedition" (i.e., The Boxer Rebellion) of 1901 qualifies, the first "peacekeeping" mission in the modern sense took place in Albania in 1913-1914, when an international force occupied the country, left derelict by the collapse of the Ottoman Empire in the First Balkan War (1911-1912), in order to establish an independent state under an imported prince. Following World War I a number of similar operations took place. From 1919 through the early 1920s the League of Nations several times borrowed military forces from the great powers for various missions, primarily in Eastern Europe and the Middle East. League forces were used to supervise the plebiscites and oversee the demarcation of frontiers for the new countries and colonies that arose from the collapse of the old empires of Germany, Austria-Hungary, Russia, and Turkey, and conduct observer missions to monitor cease fire agreements resulting from border wars, such as a potentially explosive Graeco-Bulgarian border incident in 1925 ("The War of the Dog."). But the last League activity involving military-contingents from member states was the Saar Plebiscite in 1935. By then the rise of aggressive confrontational regimes in Japan, Germany, and Italy, states that were unwilling to accept peace as an option, ended this experiment in international peacekeeping. Peacekeeping is not possible unless the great powers are more or less in agreement.
It was with the creation of the United Nations that peacekeeping began to become a commonplace of modern international relations.