Intermarium (, ) was a post-WWI geopolitical plan conceived by Józef Piłsudski to unite former Polish–Lithuanian Commonwealth lands within a single polity. The plan went through several iterations, some of which anticipated the inclusion of neighbouring states. The proposed multinational polity would have incorporated territories lying between the Baltic, Black, and Adriatic Seas. The Polish name Międzymorze (from między, "between"; and morze, "sea"), meaning "Between-Seas", was rendered into Latin as .Tomasz Piesakowski, Akcja niepodległościowa na terenie międzynarodowym, 1945–1990, 1999, p. 149:

Prospectively a federationAviel Roshwald, "Ethnic Nationalism and the Fall of Empires: Central Europe, the Middle East and Russia, 1914–1923", Routledge (UK), 2001, , p. 37Richard K Debo, Survival and Consolidation: The Foreign Policy of Soviet Russia, 1918–1921, McGill-Queen's Press, 1992, , p. 59.James H. Billington, Fire in the Minds of Men, Transaction Publishers, , p. 432Andrzej Paczkowski, The Spring Will Be Ours: Poland and the Poles from Occupation to Freedom, Penn State Press, 2003, , p. 10David Parker, The Tragedy of Great Power Politics, W. W. Norton & Company, 2001, , p. 194 of Central and Eastern European countries, the post-World War I Intermarium plan pursued by Piłsudski sought to recruit to the proposed federation the Baltic states (Lithuania, Latvia, Estonia), Finland,Mark Hewitson, Matthew D'Auria Europe in Crisis: Intellectuals and the European Idea, 1917–1957, 2012, p. 191 "… of the other national movements that had found themselves included in Piłsudski's project, especially the Lithuanians. ... The somewhat nostalgic image of 'Intermarium', the land of cultural and historical diversity destroyed by the wave of …" Belarus, Ukraine, Hungary, Romania, Yugoslavia, and Czechoslovakia.Miloslav Rechcígl, Studies in Czechoslovak history, Czechoslovak Society of Arts and Sciences in America, 1976, Volume 1, p. 282. "This new policy, which was labeled the Intermarium, or Third Europe Project, called for the establishment of ..."Fritz Taubert, "The myth of Munich 1938", 2002 p. 351 "... range détente with Germany and in the chance of creating a Polish-led 'Third Europe' or 'Intermarium' as illusory."

The proposed federation was meant to emulate the Polish–Lithuanian Commonwealth, stretching from the Baltic Sea to the Black Sea, that, from the end of the 16th century to the end of the 18th, had united the Kingdom of Poland and the Grand Duchy of Lithuania. Intermarium complemented Piłsudski's other geopolitical vision, Prometheism, whose goal was the dismemberment of the Russian Empire and that Empire's divestment of its territorial acquisitions. "Józef Pilsudski, Polish revolutionary and statesman, the first chief of state (1918–22) of the newly independent Poland established in November 1918." ("Józef Pilsudski", Encyclopædia Britannica) "Released in November 1918, [Piłsudski] returned to Warsaw, assumed command of the Polish armies, and proclaimed an independent Polish republic, which he headed." ("Piłsudski, Joseph", Columbia Encyclopedia) Timothy Snyder, Covert Polish missions across the Soviet Ukrainian border, 1928–1933 (p. 55, p. 56, p. 57, p. 58, p. 59, in Cofini, Silvia Salvatici, Rubbettino, 2005). Timothy Snyder, Sketches from a Secret War: A Polish Artist's Mission to Liberate Soviet Ukraine, Yale University Press, 2005, , (p. 41, p. 42, p. 43)"Pilsudski hoped to build not merely a Polish nation state but a greater federation of peoples under the aegis of Poland which would replace Russia as the great power of Eastern Europe. Lithuania, Belorussia and Ukraine were all to be included. His plan called for a truncated and vastly reduced Russia, a plan which excluded negotiations prior to military victory." Richard K Debo, Survival and Consolidation: The Foreign Policy of Soviet Russia, 1918–1992, p. 59, McGill-Queen's Press, 1992, ."Pilsudski's program for a federation of independent states centered on Poland; in opposing the imperial power of both Russia and Germany it was in many ways a throwback to the romantic Mazzinian nationalism of Young Poland in the early nineteenth century." James H. Billington, Fire in the Minds of Men, p. 432, Transaction Publishers,

Intermarium was perceived by some Lithuanians as a threat to their newly established independence, and by some Ukrainians as a threat to their aspirations for independence.Oleksa Pidlutsky, "Figures of the 20th century. Józef Piłsudski: the Chief who Created a State for Himself", Zerkalo Nedeli [Mirror Weekly], 3–9 February 2001, available online in Russian and in Ukrainian .Roman Szporluk, Imperiia ta natsii, Kyiv, Dukh i Litera, 2001, , section II While France backed the proposal, it was opposed by the Soviet Union and by most other Western powers."Between Imperial Temptation And Anti-Imperial Function In Eastern European Politics: Poland From The Eighteenth To Twenty-First Century". Andrzej Nowak. Accessed September 14, 2007. Within two decades of the failure of Piłsudski's grand scheme, all the countries that he had viewed as candidates for membership in the Intermarium federation had fallen to the Soviet Union or to Nazi Germany, except for Finland (which suffered some territorial losses in the 1939–40 Winter War with the Soviet Union).

Precedents

Commonwealth

A Polish–Lithuanian union and military alliance had come about as a mutual response to common threats posed by the Teutonic Order, the Golden Horde, and the Grand Duchy of Moscow. The alliance was first established in 1385 by the Union of Krewo, solemnized by the marriage of Poland's Queen Jadwiga and Lithuania's Grand Duke Jogaila of the Gediminid dynasty, who became King Władysław II Jagiełło of Poland.

A longer-lasting federation subsequently came about in 1569 in the form of the Polish–Lithuanian Commonwealth, an arrangement that lasted until 1795, i.e., until the Third Partition of the Poland.

The Polish–Lithuanian alliance thus lasted a total of 410 years, and constituted at times the largest state in Europe.

Under the Commonwealth, proposals were advanced to establish expanded, Polish–Lithuanian-Muscovite or Polish–Lithuanian–Ruthenian Commonwealths. Though the Commonwealth temporarily controlled parts of Russia and governed much of Ruthenia for centuries, these proposals were never implemented at a constitutional level.

Adam Czartoryski's plan Between the November and January Uprisings, in the period between 1832 and 1861, the idea of resurrecting an updated Polish–Lithuanian Commonwealth was advocated by Prince Adam Jerzy Czartoryski, residing in exile at the Hôtel Lambert in Paris.Marian Kamil Dziewanowski, "Polski pionier zjednoczonej Europy" ("A Polish Pioneer of a United Europe"), Gwiazda Polarna (Pole Star), Sept. 17, 2005, pp. 10–11.

In his youth, Czartoryski had fought against Russia in the Polish–Russian War of 1792; he would have done so again in the Kościuszko Uprising of 1794 had he not been arrested at Brussels on his way back to Poland. Subsequently, in 1795, he and his younger brother had been commanded to enter the Imperial Russian Army, and Catherine the Great had been so favourably impressed with them that she had restored to them part of their confiscated estates. Adam Czartoryski subsequently served the Russian emperors Paul and Alexander I as a diplomat and foreign minister, establishing an anti-French coalition during the Napoleonic Wars. Czartoryski, one of the leaders of the Polish November 1830 Uprising, had been sentenced to death after its suppression by Russia, but was eventually allowed to go into exile in France.

In Paris the "visionary""The Prince [Czartoryski] thus shows himself a visionary (emphasis added], the outstanding Polish statesman of the period between the November and January Uprisings." Dziewanowski, "Polski pionier zjednoczonej Europy," p. 11. statesman and former friend, confidant, and de facto foreign minister of Alexander I acted as the "uncrowned king and unacknowledged foreign minister" of a nonexistent Poland.Dziewanowski, "Polski pionier zjednoczonej Europy," p. 10.

In his book, Essai sur la diplomatie (Essay on Diplomacy), completed in 1827 but published only in 1830, Czartoryski observed that, "Having extended her sway south and west, and being by the nature of things unreachable from the east and north, Russia becomes a source of constant threat to Europe." He argued that Russia would have done better cultivating "friends rather than slaves". He also identified a future threat from Prussia and urged the incorporation of East Prussia into a resurrected Poland. Dziewanowski, Polski pionier zjednoczonej Europy, p. 10.

Czartoryski's diplomatic efforts anticipated Piłsudski's Prometheist project in linking efforts for Polish independence with similar movements of other subjugated nations in Europe, as far east as the Caucasus Mountains, most notably in Georgia.Dziewanowski, "Polski pionier zjednoczonej Europy," pp. 10–11.

Czartoryski aspired above all to reconstitute—with French, British, and Ottoman support—a sort of "pan-Slavic" Polish–Lithuanian Commonwealth federated with the Czechs, Slovaks, Hungarians, Romanians, and all the South Slavs of the future Yugoslavia. Poland, in his concept, could have mediated the conflicts between Hungary and the Slavs, and between Hungary and Romania. Dziewanowski, "Polski pionier zjednoczonej Europy," p. 11. The plan seemed achievable"Adam Czartoryski's great plan, which had seemed close to realization (emphasis added) during the Spring of Nations in 1848–49, failed..." Dziewanowski, "Polski pionier zjednoczonej Europy," p. 11. during the period of national revolutions in 1848–49 but foundered on lack of western support, on Hungarian intransigence toward the Czechs, Slovaks, and Romanians, and on the rise of German nationalism.Dziewanowski, "Polski pionier zjednoczonej Europy", p. 11.

Marian Kamil Dziewanowski writes that "the Prince's endeavour constitutes a [vital] link [between] the 16th-century Jagiellon [federative prototype] and Józef Piłsudski's federative-Prometheist program [that was to follow after World War I]."

Józef Piłsudski's Międzymorze

Józef Piłsudski's strategic goal was to resurrect an updated, democratic form of the Polish–Lithuanian Commonwealth, while working for the disintegration of the Russian Empire, and later the Soviet Union, into its ethnic constituents. (The latter was his Prometheist project.) Piłsudski saw an Intermarium federation as a counterweight to Russian and German imperialism.

According to Dziewanowski, the plan was never expressed in systematic fashion but instead relied on Piłsudski's pragmatic instincts.Kenneth F. Lewalski (March 1972). "Review of Joseph Pilsudski: A European Federalist, 1918–1922, by M. K. Dziewanowski". Journal of Modern History. Accessed September 16, 2007. According to British scholar George Sanford, about the time of the Polish–Soviet War of 1920 Piłsudski recognised that the plan was not feasible.George Sanford, Democratic Government in Poland: Constitutional Politics since 1989. Palgrave Macmillan 2002. . pp. 5–6.

Opposition