List of proposed state mergers
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This is a list of proposed state mergers, including both current and historical proposals originating from sovereign states or organizations. The entities listed below differ from separatist movements in that they would form as a merger or union of two or more existing states, territories, colonies or other regions, becoming either a federation, confederation or other type of unified sovereign state.
Historical[edit]
Early modern period[edit]
| Proposed state | Components | Time period | Successful? | Notes |
|---|---|---|---|---|
 Swiss Confederation |  Uri Schwyz Unterwalden | 1307 | Yes | Three cantons formed the initial Confederation in the 1307 Rütlischwur, followed by the 1315 Pact of Brunnen; ten more cantons joined over the life of the Confederacy. |
 Kalmar Union |  Danish Realm Kingdom of Norway Kingdom of Sweden | 1397-1523 | Yes | The Kalmar Union was a personal union between the Kingdoms of Denmark, Norway, and Sweden. Established in 1397 under the rule of Queen Margaret I, the union aimed to create a single monarch ruling over these three kingdoms. |
 Polish–Lithuanian Commonwealth |  Kingdom of Poland Grand Duchy of Lithuania | 1569 | Yes | Union of Lublin |
 Polish–Lithuanian–Muscovite Commonwealth | Polish–Lithuanian Commonwealth Tsardom of Russia | 1574–1658 | No | |
 Iberian Union | .svg){kind=small} Crown of Castile Crown of Aragon.svg){kind=small} Crown of Portugal | 1580–1640 | Yes | Portugal became part of the realms of the Spanish Habsburg (Casa de Austria) following the death of Henry I of Portugal but resumed its independence 60 years later. |
 Polish–Lithuanian–Ruthenian Commonwealth | Polish–Lithuanian Commonwealth Cossack Hetmanate | 1658–1659 | No | Treaty of Hadiach |
 Kingdom of Great Britain |  Kingdom of England Kingdom of Scotland | 1707 | Yes | Though having been ruled since 1603 in personal union when James VI, already king of Scotland, succeeded to the English crown, both countries remained separate sovereign nation states until 1707 when the Treaty of Union unified them into a single entity. |
 United States | Connecticut Delaware Georgia Maryland Massachusetts New Hampshire New Jersey New York North Carolina Pennsylvania Rhode Island South Carolina Virginia | 1775–1788 | Yes | Constitution of the United States is ratified by the Thirteen Colonies, replacing the Articles of Confederation and thereby forming a Federal government. |
 Dutch Republic | Dutch Republic United Belgian States | 1789–1790 | No | During the Brabant Revolution, Hendrik van der Noot, Prime Minister of the young Belgian state proposed incorporating the confederation into the Dutch Republic. Later Willem I admitted that his idea to unite the Low Countries under the United Kingdom of the Netherlands was influenced by van der Noot's proposal.[1][2] |
19th century[edit]
| Proposed state | Components | Time period | Successful? | Notes |
|---|---|---|---|---|
 United Kingdom of Great Britain and Ireland | Kingdom of Great Britain Kingdom of Ireland | 1800 | Yes | Acts of Union 1800. Most of Ireland left the union as the Irish Free State in 1922, while Northern Ireland remained part of the United Kingdom. |
| Northern Confederacy | Connecticut Massachusetts New York New Hampshire New Jersey Pennsylvania Rhode Island Vermont Also invited: Lower Canada New Brunswick Newfoundland Colony Nova Scotia Prince Edward Island Upper Canada | 1804 | No | The Northern Confederacy was a conspiracy headed by Senator Timothy Pickering to separate the Northeastern United States and The British Colonies in North America into one Confederation.[3][4] |
 United Kingdom of the Netherlands | Sovereign Principality of the United Netherlands Provisional Government of Belgium (1814) | 1815 | Yes | |
 Gran Colombia |  United Provinces of New Granada Second Republic of Venezuela Real Audiencia of Quito | 1819–1830 | Yes | |
 First Mexican Empire | First Mexican Empire Captaincy General of Guatemala | 1822–1823 | Yes | Central America was annexed into the First Mexican Empire. After the dissolution of the Empire only Chiapas choose to remain part of Mexico, the rest became the Federal Republic of Central America. Costa Rica in particular was split between inner factions in favor and against the annexation, ending in a Civil War. The pro-Mexican provinces declared membership but were not recognized by the pro-independence provinces. |
 Federal Republic of Central America |  El Salvador Honduras Nicaragua Guatemala  Los Altos Costa Rica | 1823–1841 | Yes | |
| Costa Rica |  Costa Rica Nicoya | 1824 | Yes | Annexation of Nicoya |
 Federation of the Andes | Colombia Peru Bolivia | 1826 | No | Proposed merger of the countries liberated by Simón Bolivar into a single state. |
 Peru–Bolivian Confederation |  Peru Bolivia | 1829–1836 | Yes | |
 Italian United Provinces |  Duchy of Parma Duchy of Modena and Reggio Grand Duchy of Tuscany Romagna (part of State of the Church) | 1831 | Yes | |
 Rio Uruguay |  Juliana Riograndense Uruguay | 1836 | No | Riograndense forces were financially and (indirectly) militarily supported by the Uruguayan government led by José Fructuoso Rivera.[5] The Uruguayans had the intention of creating a political union with the Riograndense Republic to create a new stronger state.[5] Juliana Republic was founded in 1839 and formed a confederation with Riograndense, but Juliana itself collapsed less than four months after its founding. |
 United States | United States Upper Canada | 1837–1838 | No | Rebellions of 1837–1838. Republicans in Upper Canada pursued annexation by the United States.[6] |
| United Kingdom of Ecuador, Peru and Bolivia |  Ecuador Peru Bolivia | 1846 | No | Plan by Juan José Flores to re-conquer the former Bourbon Crown territories of the Viceroyalty of Peru.[7] |
 Confederated States of Plata | Argentine Confederation Estado oriental Del Uruguay Paraguay | 1850 | No | The Confederated States of the Río de la Plata were a State proposal devised by Domingo Faustino Sarmiento in the book Argirópolis or the capital of the confederated states of the Río de la Plata, with its capital on Martín García Island, would be founded. This idea did not prosper due to the historical changes produced by the battle of Caseros in 1852.[8] |
| Danubian Confederation[9] |  Hungary Romania Vojvodina Croatia Slovakia | 1850 | No | The Hungarian Statesman Lajos Kossuth (1802–1894) attempted at different stages of his exile following the Hungarian War of Independence in 1849 to organize a Danubian Confederation. He intended to accommodate the forces of nationalism within the Danubian basin while preserving Hungary's territorial integrity and replacing Austria's position in the European balance of power[9] |
 Federation of Central America | El Salvador Honduras Nicaragua | 1852 | Yes | Second attempt at unification that lasted for less than a month. |
 Liberia | Republic of Liberia Republic of Maryland | 1854–1857 | Yes | Republic of Maryland was officially named Maryland in Liberia during its independence referendum on 29 May 1854. |
 United Principalities of Moldavia and Wallachia |  Principality of Moldavia Principality of Wallachia | 1859 | Yes | Unification of Moldavia and Wallachia; becomes Kingdom of Romania in 1881. |
| United Provinces of Central Italy |  Duchy of Parma Duchy of Modena and Reggio Grand Duchy of Tuscany Romagna | 1859 | Yes | |
 Kingdom of Sardinia | Kingdom of Sardinia United Provinces of Central Italy | 1860 | Yes | |
 Belgium–Netherlands Confederation |  Belgium Netherlands | 1860 | No | Belgian Prime Minister Charles Rogier proposed a personal union of Belgium and the Netherlands due to fear of French invasion.[10] |
 Confederate States of America |  State of South Carolina State of Mississippi State of Florida State of Alabama State of Georgia State of Louisiana State of Texas Commonwealth of Virginia State of Arkansas State of North Carolina State of Tennessee | 1861-1865 | Yes | American Civil War |
 Spanish Empire | Spanish Empire First Dominican Republic | 1861 | Yes | In 1861 general Pedro Santana asked Queen Isabella II of Spain to retake control of the Dominican Republic after a period of only 17 years of independence. Spain accepted his proposal and made the country a colony again.[11][12] |
 Kingdom of Greece | Kingdom of Greece United States of the Ionian Islands | 1864 | Yes | Treaty of London (1864) |
 North German Confederation |  Kingdom of Prussia Kingdom of Saxony Grand Duchy of Hesse Duchy of Mecklenburg-Schwerin Grand Duchy of Mecklenburg-Strelitz Grand Duchy of Oldenburg Saxe-Weimar-Eisenach Duchy of Anhalt Duchy of Brunswick Duchy of Saxe-Altenburg Saxe-Coburg-Gotha Saxe-MeiningenVarious other small principalities and free cities | 1866 | Yes | Following the Austro-Prussian War of 1866 and the annexation by Prussia of Austria's northern German ally states Otto von Bismarck proposed to unify Prussia and its own German ally states into a single Federation. Consequently the North German Constitution was adopted, with the provision that the southern German minor states could enter into the union when politically feasible. |
| South German Confederation |  Bavaria Württemberg Baden Hesse-Darmstadt | 1866 | No | Proposed union of the southern German states that was discussed in the mid-19th century. The idea of a confederation emerged in the aftermath of the Austro-Prussian War of 1866, which resulted in the dissolution of the German Confederation and the emergence of the North German Confederation under the leadership of Prussia. The southern German states, including Bavaria, Württemberg, Baden, and Hesse-Darmstadt, were concerned about the growing power of Prussia and the dominance of northern German states in the new confederation. They sought to form their own union, which would allow them to retain their autonomy while also providing for mutual defense and economic cooperation. |
 Austro-Hungarian Empire |  Austria Hungary | 1867 | Yes | Unification of Austro-Hungarian Empire |
 Dominion of Canada | Province of Canada Province of New Brunswick Province of Nova Scotia | 1867 | Yes | Canadian Confederation |
 United States | United States Greenland | 1867–2019 | No | The idea for the United States to buy Greenland was first proposed during the administration of President Andrew Johnson, when, in 1867, Secretary of State William H. Seward unsuccessfully proposed buying Greenland and Iceland from the Danish Kingdom. A post-World War II bid was also declined by Denmark.[13] In 2018 and 2019, President Donald Trump spoke to aides about acquiring the island; Greenlandic and Danish officials firmly rebuffed the suggestion that the island could be sold.[14][15] |
 Antillean Confederation |  Captaincy General of Cuba Captaincy General of Puerto Rico Second Dominican Republic | 1869–1870 | No | Proposed by Ramón Emeterio Betances. |
| German Empire | Lesser Germany: North German Confederation Kingdom of Bavaria Kingdom of Württemberg Grand Duchy of Baden Grand Duchy of Hesse Alsace-LorraineGreater Germany also included: Austrian Empire | 1871 | Yes | The German question regarding the competing ideas of "Greater Germany" and "Lesser Germany" (whether or not a united Germany should include the Austrian Empire) was settled with the Austro-Prussian War in 1866, in which Prussia assumed leadership of the various minor German nation states. The Unification of Germany (excluding Austria) was completed after German victory over the French in the Franco-Prussian War. |
| Bulgaria–Romania |  Bulgaria Romania | 1878–1879 | No | Proposed personal union, German prince Alexander of Battenberg is elected instead.[16] |
 United States of Peru–Bolivia | Peru Bolivia | 1880 | No | Proposed state by Nicolás de Piérola and Narciso Campero, also called the Federal Republic of the Incas.[17] |
| Kingdom of Spain | Kingdom of Spain Captaincy General of the Philippines | 1880–1898 | No | By the Propaganda Movement led by Filipinos educated in Europe which advocated the Philippine islands be converted from a colony to a province of Spain.[18] |
| Estonian–Finnish federation |  Estonia Finland | 1881–1941 | No | The matter was discussed on December 8, 1917, at the Estonian Council of Elders, where Jaan Raamot spoke about the positive attitude of Pehr Evind Svinhufvud, Speaker of the Senate of Finland. In his speech to the Council of Elders, Estonian Politician Konstantin Päts supported the Union and welcomed the idea. |
| Polynesian Confederation |  Kingdom of Fiji Kingdom of Hawaii Kingdom of Samoa Kingdom of Tahiti Kingdom of Tonga | 1882 | No | During the period of European colonization, king Kalākaua of Hawaii proposed a Polynesian Confederation.[19][20][21] |
| Principality of Bulgaria | Bulgaria Autonomous Province of East Rumelia | 1885–1886 | Yes | After Bulgaria defeated Serbia in the Serbo-Bulgarian War of 1885, Bulgaria nearly doubled in size when East Rumelia was incorporated within its borders. Bulgaria officially annexed it from the Ottoman Empire in 1885. |
| Bulgaria–Romania | Bulgaria Romania | 1886–1887 | No | Proposed personal union, rejected by Carol I of Romania due to Russian pressure.[16] |
| Dominion of Canada | Dominion of Canada Jamaica | 1890 | No | In the late 19th century, there was some discussion of some form of political union between Canada and Jamaica.[22] |
 Greater Republic of Central America |  El Salvador Honduras NicaraguaConsidered joining:  Costa Rica Guatemala | 1895–1898 | Yes | |
| Anglo-American union | United Kingdom United States | 1860–1914 | No | Numerous prominent transatlantic thinkers proposed a union of the United States and the United Kingdom.[23] |
20th century[edit]
| Proposed state | Components | Time period | Successful? | Notes |
|---|---|---|---|---|
 Commonwealth of Australia |  New South Wales Queensland South Australia Tasmania Victoria Western AustraliaAlso invited:  Colony of Fiji Colony of New Zealand | 1901 | Yes | Federation of Australia. New Zealand had many disagreements with the Australian government and decided to not join. Fiji also did not join. |
| Franco-British Union |  France United Kingdom | 1904–1956 | No | A Franco-British Union is a concept for a union between the two independent sovereign states of the United Kingdom and France. Such a union was proposed during certain crises of the 20th century; it has some historical precedents. In April 1904 France and the United Kingdom signed a series of agreements, known as the Entente Cordiale, which marked the end of centuries of intermittent conflict between the two powers, and the start of a period of peaceful co-existence. Nationalist political leaders from both sides were uncomfortable with the idea of such a merging. |
 Union of South Africa |  Cape Colony Colony of Natal Orange River Colony Transvaal Colony | 1909 | Yes | Union of South Africa |
| Balkan Socialist Federation |  Kingdom of Yugoslavia Principality of Albania Kingdom of Bulgaria | 1910–1916 | No | |
 Imperial Federation | United Kingdom Ireland Dominion of Canada Commonwealth of Australia Dominion of Newfoundland Dominion of New Zealand Union of South Africa India | 1911–1937 | No | The British Empire was composed of many states with vastly different constitutions and goals to pursue. Groups like the Imperial Federation League advocated for a political union between the territories of the Empire that could establish a "permanent binding force" between them.[24] Each dominion would be guaranteed representation on equal footing with the United Kingdom in an Imperial Parliament.[25] Ireland would also have been presented representation as an alternative to home rule, and it was deemed possible that an autonomous India could one day join as well. First discussed by heads of government at the 1911 Imperial Conference, and for a second time at the 1937 Imperial Conference where it was eventually dismissed. |
| Dominion of Canada | Dominion of Canada The Bahamas | 1911 | No | In 1911, at the request of the Bahamian House of Assembly, the Canadian and the Bahamian governments began serious negotiations for Bahamian accession to the Canadian confederation.[26] However, a racial panic ignited by the migration of over one thousand African-Americans fleeing violence in Oklahoma derailed the discussions. Prime Minister Wilfrid Laurier turned against the idea, citing incompatible "ethnical origin". After Laurier lost the September 1911 federal election, Bahamian Governor William Grey-Wilson travelled to Canada to reopen accession talks with newly elected PM Robert Borden.[27] In a meeting between Grey and Borden on 18 October 1911, Borden rejected the possibility of taking the Bahamas into the Canadian confederation. His reasoning was that the events of the past year had proved that Canadian public opinion would not countenance the admission of a majority-black province. The British Colonial Office concurred: "No doubt for the moment the Dominion government would safeguard their interests, but there are signs of the rise of a colour question in Canada and in any case it cannot be long before U.S. opinion gives the tone to Canada in regard the Negro."[28] |
 Kingdom of Greece |  Cretan State Kingdom of Greece | 1913 | Yes | Crete rebelled against Ottoman rule during the Cretan Revolt of 1866–69 and used the motto "Crete, Enosis, Freedom or Death". The Cretan State was established after the intervention of the Great Powers, and Cretan union with Greece occurred de facto in 1908 and de jure in 1913 by the Treaty of Bucharest. |
| Hungary–Romania | Kingdom of Romania Republic and Kingdom of Hungary | 1917–1920 | No | Federation or personal union between the Kingdom of Romania and the Kingdom/Republic of Hungary under one monarch. Proposals were the most active in 1919 and 1920, but they continued to exist up to the Second World War.[29][30][31][32] |
 United States of Poland | Kingdom of Poland  Kingdom of Lithuania  Kingdom of Galicia and Lodomeria  Belarusian Democratic Republic | 1917 | Partial | |
| Kingdom of Yugoslavia |  Kingdom of Serbia Kingdom of Montenegro State of Slovenes, Croats and Serbs | 1918 | Yes | Creation of Yugoslavia |
| Kingdom of Romania | Kingdom of Romania Moldavian Democratic Republic Bukovina Transylvania | 1918 | Yes | Great Union, Union of Bessarabia with Romania, Union of Bukovina with Romania, Union of Transylvania with Romania |
| Intermarium | Belarusian People's Republic Czechoslovak Republic Estonia Finland Hungarian People's Republic Latvia Lithuania Polish Republic Kingdom of Romania Ukrainian People's Republic Kingdom of Yugoslavia Kingdom of Bulgaria | November or December 1918 | No | Also called "Międzymorze" in Polish. Suggested shortly after World War I to combat the influences of Germany and Russia. |
| Transcaucasian Democratic Federative Republic |  Democratic Republic of Georgia Democratic Republic of Armenia Azerbaijan Democratic Republic | 1918 | Yes | A short-lived South Caucasian state that extended across what are now the modern-day countries of Georgia, Armenia and Azerbaijan plus parts of Eastern Turkey as well as Russian border areas. The state only lasted for a month before Georgia declared independence, followed shortly by Azerbaijan and Armenia. |
 Weimar Republic | Weimar Republic Republic of German-Austria | 1918–1919 | No | Following the disintegration of Austria-Hungary in the final days of World War I the German-speaking territories of the former Austria-Hungary attempted to begin a process of integration into Weimar Germany. The Allies did not favor the idea, and forced the Austrian rump state to sign the Treaty of Saint Germain, which prohibited Austria from uniting with Germany. |
| Ukrainian People's Republic | Ukrainian People's Republic West Ukrainian People's Republic | 1919 | Yes | Act Zluky |
 Patria Grande |  Argentina Bolivia Chile Colombia Costa Rica Cuba Dominican Republic El Salvador Ecuador Guatemala Honduras Mexico Nicaragua Panama Paraguay Peru Puerto Rico Uruguay Venezuela | 1922 | No | The concept of a shared homeland or community encompassing all of Spanish America, and sometimes all of Latin America and the Caribbean. The term is associated with political ideas of Ibero-American integration, rejecting the balkanization of the Spanish Empire in the Americas that followed the Spanish American wars of independence. The term may be also used to talk specifically about projects of Hispanic American unity held by Simón Bolívar and José de San Martín. |
 Union of Soviet Socialist Republics |  Byelorussian SSR Russian SFSR Transcaucasian SFSR Ukrainian SSR | 1922 | Yes | Treaty on the Creation of the Union of Soviet Socialist Republics |
| Union of South Africa | Union of South Africa Colony of Southern Rhodesia | 1922 | No | The 1922 Southern Rhodesian government referendum was held in the colony on 27 October 1922. Voters, almost all of them White, were given the options of establishing responsible government or joining the Union of South Africa.[33] After 59% voted in favour of responsible government, it was officially granted on 1 October 1923. |
| Baltoscandia | Denmark Sweden Finland Norway Iceland Estonia Lithuania Latvia | 1928–1960 | No | The term Baltoscandia was first used by Sten de Geer in an article in "Geografiska Annaler" in 1928 and further developed by Kazys Pakštas.[34] He envisioned Baltoscandia as an economic, political and military unit.[35] Kazys Pakštas proposed that one of the ways for the small nations to withstand the influence coming from the large ones is to unite and to cooperate more closely among each other. As he mentions, unification is possible only among nations that are similar by their size, geographical environment, religion and culture. |
 Greater Indonesia | Dutch East Indies British Malaya Crown Colony of Sarawak Crown colony of North Borneo Protectorate of Brunei Crown colony of Singapore Portuguese Timor | 1928 | No | A political concept that sought to bring the so-called Malay race together by uniting the territories of Dutch East Indies (and Portuguese Timor) with the British Malaya and British Borneo. It was espoused by students and graduates of Sultan Idris Training College for Malay Teachers in the late 1920s, and individuals from Sumatra and Java including Mohammad Yamin and Sukarno in the 1950s. Indonesia Raya was later adapted as the name of the Indonesian national anthem in 1924. |
 German Reich | German Reich Federal State of Austria | 1938 | Yes | Anschluss |
 Turkey | Turkey Hatay State | 1939 | Yes | On 2 September 1938 the Sanjak of Alexandretta declared itself separate from the French Mandate of Syria and Lebanon, becoming the Hatay State. On 29 June 1939, the legislature voted to merge with Turkey. |
| Polish–Czechoslovak confederation | Polish Republic Czechoslovak Republic | 1939–1948 | No | Proposed by Władysław Sikorski. |
| Greek–Yugoslav confederation | Strictest definition: Kingdom of Greece Kingdom of Yugoslavia Loosest definition also includes:  Albanian Kingdom Kingdom of Bulgaria Kingdom of Romania | 1942–1944 | No | The Greek-Yugoslav confederation was a political concept during World War II, sponsored by the United Kingdom and involving the Greek government-in-exile and the Yugoslav government-in-exile. The two governments signed an agreement pushing the proposal ahead, but it never got beyond the planning stage because of opposition from within the Greek and the Yugoslav governments, real world events, and the opposition of the Soviet Union. The proposal envisioned the creation of a confederation of Greece and Yugoslavia. |
 Soviet Union | Soviet Union Tuvan People's Republic | 1943–1944 | Yes | Tuvan underwent intense Russification of social and economic practices, and virtually all remaining opposition to Stalinist policy was eradicated. The Soviets desired the mineral resources of the republic and a permanent end to Mongolian-Chinese geopolitical intrigues in the region. This process culminated in the absorption of Tuva in 1944, under the rule of General Secretary Salchak Toka and his wife, Head of State Khertek Anchimaa-Toka.[36] |
 United Arab Kingdom | Transjordan Palestine | 1945–1972 | No | King Hussein's federation plan: In the late 1940s and early 1950s, there were discussions of a potential merger between Israel and Jordan, which was then known as Transjordan. The idea was initially proposed by King Abdullah I of Jordan, who sought to create a larger Arab state in the region that would include both Jordan and Palestine. The proposal was also supported by some Israeli politicians who believed that a union with Jordan would help to resolve the ongoing conflict between Jews and Arabs in the region. |
 Ewe Land[37] | French Togoland British Togoland | 1945–1956 | No | In 1945 various members of Ewe and wider Togolese leadership began the construction of political organizations which sought to decolonize French Togoland. These developed as the Comité de l'Unité Togolaise, led by Sylvanus Olympio, and the Mouvement la Jeunesse Togolaise. Both possessed political platforms that included the reunification of the French Togoland and British Togoland.[37] |
| Maghreb Federation |  Algeria Libya Mauritania Morocco Spanish Morocco Spanish Sahara Tunisia | 1945-1958 | No | The first charter to create a Maghreb Federation was signed in Tunisia and Morocco in May 1945, but only became effective in 1958.[38] |
| Balkan Federation |  Socialist Federal Republic of Yugoslavia People's Socialist Republic of Albania People's Republic of Bulgaria | 1946–1948 | No | Josip Broz Tito came extremely close to persuading Albania to accept integration into Yugoslavia, but relations cooled in 1948 over fears that Yugoslavia only intended to use Albania for raw materials, subsequently resulting in the expulsion of Yugoslav diplomats. Yugoslav/Bulgarian negotiations fell through when Moscow attempted to force both countries into accepting Soviet control over the merge, which caused Yugoslavia to withdraw from negotiations and precipitated the Tito–Stalin split. |
 India | India Junagadh State Other states | 1947–1948 | Yes | Political integration of India, Annexation of Junagadh |
| United States of Indonesia |  Bangka Banjar Biliton Central Java East Borneo East Indonesia East Java East Sumatra Great Dayak Indonesia
| 1946–1949 | Yes | Following discussions between Dutch authorities and Indonesian nationalist leaders, the Linggadjati Agreement was signed on 15 November 1946, in which the unilaterally declared Republic of Indonesia agreed to the principle of a federal Indonesia including the territory controlled by the Republic and other territory in the region which the Dutch controlled at that point. The Dutch then organised the December 1946 Denpasar Conference, which led to the establishment of the State of East Indonesia, followed by a state in West Borneo. Further states were set up in former territory of the Republic after they were conquered by the Dutch in 1947. Further Dutch military action faced increasing resistance from governments of the states they had established, and this combined with international pressure caused the Dutch–Indonesian Round Table Conference to take place in The Hague from August to November 1949. This Conference resulted in the Dutch agreeing to hand over sovereignty to a federal union of these states, which officially became the Republic of the United States of Indonesia. This federation lasted only a year, as its member states agreed to dissolve themselves into a unitary state, the last stage of which took place on 17 August 1950. |
| India | India Princely states | 1947–1950 | Yes | Instrument of Accession |
 Pakistan | Pakistan Princely states | 1947–1950 | Yes | Instrument of Accession |
| India | India Hyderabad | 1948 | Yes | Annexation of Hyderabad |
 Dominion of Canada | Dominion of Canada Dominion of Newfoundland | 1948–1949 | Yes | In two rounds of referendums in 1948, the Dominion of Newfoundland had the choice of becoming an independent state, merging with the Dominion of Canada, or remaining as a British dominion. The Newfoundland Act of 1949, an act of the Parliament of the United Kingdom, confirmed and gave effect to the Terms of Union agreed to between the then-separate Dominions of Canada and Newfoundland on 23 March 1949. |
| Netherlands–Indonesia Union | Netherlands United States of Indonesia | 1949–1956 | Partial | After the Netherlands had signed a truce with the United States of Indonesia, a transfer of sovereignty took place on 27 December 1949. As part of the Linggadjati Agreement, the Netherlands–Indonesia Union was founded. The Union was abolished when Indonesia left in 1956.[39] |
| State of the Fertile Crescent |  Jordan Iraq Syria Lebanon Palestine | 1949–1958 | No | Fertile Crescent Plan |
| Dominion of Canada | Dominion of Canada Bermuda | 1949 | No | In 1949 Henry Vassey, then Chairman of the Bermuda Trade Development Board, urged the House of Assembly of Bermuda to pursue a political union with Canada. Four Methodist church congregations in Bermuda are part of the United Church of Canada, forming Bermuda Presbytery of the United Church's Maritime Conference headquartered in Sackville, New Brunswick. The same Salvation Army Church territory serves both Canada and Bermuda with many of their pastors travelling between countries.[40] In January 2009, Nova Scotia's Premier, Rodney MacDonald, and the Premier of Bermuda, Ewart Brown, signed a five-year agreement that would strengthen Nova Scotia's ties with Bermuda and enhance service export opportunities, tourism, transportation and health links in both jurisdictions. Bermuda's ties to Canada include the Institute of Chartered Accountants of Bermuda being overseen by Canada's Chartered Professional Accounting profession. |
| Franco-German Federation |  West Germany France | 1950 | No | The idea of a Franco-German federation was a proposed merger between France and Germany after the end of World War II. The idea was promoted by French politician Robert Schuman in his declaration on May 9, 1950, which is now celebrated as Europe Day. The aim of the proposal was to create a lasting peace between the two countries and to promote economic cooperation.[1] The Franco-German federation proposal envisioned a common government, currency, and military. It also sought to establish a European Coal and Steel Community (ECSC), which would integrate the coal and steel industries of France and Germany. The ECSC was created in 1952 and was the first step toward the creation of the European Union.[41][42] |
 Greece | Greece Cyprus | 1950 | No | An unofficial referendum on enosis (reunification) with Greece was held in Cyprus between 15 and 22 January 1950, and the proposal was approved by 95.71% of those taking part. |
| Indonesia | Indonesia Netherlands New Guinea | 1950–1969 | Yes | Following Dutch recognition of Indonesian Independence, Indonesia continued to claim the remaining Dutch territory in the region, Netherlands New Guinea, as its rightful territory. The dispute escalated into low-level conflict in 1962 following Dutch moves in 1961 to establish a New Guinea Council. Facing diplomatic pressure from the United States, fading domestic support and continual Indonesian threats to invade the territory, the Netherlands decided to relinquish control of the disputed territory in August 1962. Following a short period of UN administration, the territory was transferred to Indonesia on 1 May 1963. |
 Federation of Rhodesia and Nyasaland |  Protectorate of Nyasaland Protectorate of Northern Rhodesia Colony of Southern Rhodesia | 1953 | Yes | |
| Afghanistan-Pakistan Confederation[43] |  Kingdom of Afghanistan Dominion of Pakistan | 1953–1954 | No | Afghanistan–Pakistan Confederation plan referred to a plan proposed between the governments of Afghanistan and Pakistan between 1953 and 1954 to merge both countries under a single confederation. These plans were started by Ayub Khan, the president of Pakistan and the monarchy of Afghanistan under King Zahir Shah. President Zia-ul-Haq too was for such confederation. "Charles Wilson recalled a map that Zia had also shown to him in which overlay indicated the goal of a confederation embracing first Pakistan and Afghanistan and eventually Central Asia and Kashmir. Zia further explained about the Pakistan-Afghanistan confederation in which Pakistanis and Afghans could travel freely back and forth without passports."[44] General Akhtar Abdur Rahman, considered Zia's right-hand man and more importantly the DG-ISI (1979–1987), himself a Pashtun, "also shared Zia’s vision of a post-Soviet "Islamic Confederation" composed of Pakistan, Afghanistan, Kashmir and even the states of Soviet Central Asia."[45] |
| West Germany | West Germany Saar Protectorate | 1955–1957 | Yes | 1955 Saar Statute referendum. Saarland became a state of Germany and exited France's economic union. |
| United Kingdom | United Kingdom Crown Colony of Malta | 1956 | No | 1956 Maltese United Kingdom integration referendum |
 Ghana | Gold Coast British Togoland | 1956 | Yes | In the 1956 British Togoland status plebiscite 58% of voters supported a union with Ghana, whereas 42% voted in favor of remaining a United Nations Trust Territory under British control until neighbouring French Togoland had decided its future.[46] |
 North Borneo Federation |  Crown Colony of North Borneo Crown Colony of Sarawak Protectorate of Brunei | 1956–1960 | No | Sarawak and North Borneo merged with the independent Federation of Malaya several years later, forming Malaysia, while Brunei later became an independent state on its own. |
 United States of Latin Africa | Angola Belgian Congo Ruanda-Urundi French Congo Ubangi-Shari French Chad French Cameroon French Gabon Spanish Guinea São Tomé and Príncipe | 1957–1959 | No | Proposed union of Romance-language-speaking Central African countries envisioned by Barthélemy Boganda. Boganda first called for it in May 1957.[47] The idea's implementation was cut short by Boganda's death in a plane crash on 29 March 1959.[48] Boganda viewed this entity to be a counterweight to the powerful British-influenced southern bloc of South Africa and the Federation of Rhodesia and Nyasaland.[47] |
| Melanesian Federation | Dutch New Guinea Solomon Islands Protectorate Territory of Papua and New Guinea | 1957 | No | Australian Governor General John Kerr was a vocal proponent of the idea of a Melanesian Federation as a solution to the West Papua dispute.[49][50][51] |
 Cameroon | Cameroon Spanish Guinea | 1958–1963 | No | The Equatoguinean independence leader Enrique Nvo and the first formal Equatoguinean political party, IPGE, advocated for independence from Spain and a political union between Cameroon and Equatorial Guinea.[52] The idea of a union was deemed unfeasible after the 1963 Spanish Guinean autonomy referendum.[52] |
 Union of African States | Ghana Guinea Mali (joined in 1961) | 1958–1963 | Yes | The union planned to develop a common currency and unified foreign policy amongst members; however, none of these proposals were implemented by the countries. The union was the first organization in Africa to bring together former colonies of the British and the French. Although the union was open to all independent states in Africa, no other states joined. |
 West Indies Federation |  British Barbados British Jamaica British Leeward Islands (except the Virgin Islands) British Trinidad and Tobago British Windward IslandsAlso invited:  Crown Colony of the Bahama Islands British Guiana British Honduras British Virgin Islands | 1958 | Yes | The expressed intention of the Federation was to create a political unit that would become independent from Britain as a single state. However, before that could happen, the Federation collapsed due to internal political conflicts. |
 United Arab Republic |  Republic of Egypt Syrian Republic | 1958 | Yes | A short-lived Pan-Arab state. |
| United Arab States | United Arab Republic Mutawakkilite Kingdom of Yemen | 1958 | Yes | Loose confederation between the United Arab Republic and North Yemen. |
 Arab Federation | Kingdom of Iraq Hashemite Kingdom of Jordan | 1958 | Yes | An attempt to unify the two Hashemite kingdoms of Iraq and Jordan. While successful, the short-lived union was disestablished after a military coup deposed Faisal II of Iraq. |
| Sahel-Benin Union |  Republic of Upper Volta Niger Republic of Dahomey Ivory Coast | 1958 or 1959 ?–1959 | Yes | |
| Mali Federation |  Senegal Mali | 1959–1960 | Yes | Senghor became very wary of unification efforts after the failed experiment and despite attempts to create other federations in West Africa and with Senegal's neighbours, Senghor often restrained these efforts and they only progressed after his rule.[53] In addition, as the first failed unification experiment in Africa, the Mali Federation served as a lesson in future attempts at unification throughout the continent.[54] Keïta became more assertive with pushing his ideology after the collapse of the federation and refused diplomatic relations with Senegal for many years.[55] Nonetheless, Mali under Keïta still pursued the goal of West African unity but did so in a variety of different international connections.[56] |
 Somali Republic | Trust Territory of Somalia State of Somaliland | 1960 | Yes | On 26 June 1960 the former British Somaliland protectorate briefly obtained independence as the State of Somaliland, with the Trust Territory of Somaliland following suit five days later.[57][58] The following day, on 27 June 1960, the newly convened Somaliland Legislative Assembly approved a bill that would formally allow for the union of the State of Somaliland with the Trust Territory of Somaliland on 1 July 1960.[59] Following the collapse of Barre's government in early 1991, local authorities, led by the SNM, unilaterally declared independence from Somalia on 18 May of the same year and reinstated the borders of the former short-lived independent State of Somaliland. |
 Soviet Union | Soviet Union People's Republic of Bulgaria | 1960 | No | The leader of the People's Republic of Bulgaria, Todor Zhivkov, suggested in the early 1960s that the country should become a union republic, but the offer was rejected.[60][61][62] |
| East African Federation |  Kenya Colony Tanganyika Territory Uganda Protectorate Sultanate of Zanzibar | 1960–1964 | No | Proposed political union between the four territories (one colony, two protectorates and one League of Nations mandated territory) under British rule in East Africa in the 1960s. Tanganyika proposed to delay its imminent independence in 1960 so that the four territories might achieve independence together as one federation. In 1963 the leaders of all of the territories (some now independent) pledged to work towards a federation by 1964, but ultimately disputes over the nature of the federation and concerns about sharing power led to the collapse of effort to federate. Only Tanganyika and Zanzibar eventually united in 1964. |
 Cameroon | Cameroon British Cameroon | 1961 | Partially (Southern Cameroons) | In the 1961 British Cameroons referendum, the Christian majority in the south of British Cameroon voted to integrate with Cameroon, whereas the Muslim-majority Northern areas voted to integrate with Nigeria. |
 Nigeria | Nigeria British Cameroon | Partially (Northern Cameroons) | ||
| India | India Portuguese State of India | 1961 | Yes | Annexation of Dadra and Nagar Haveli, Annexation of Goa |
| India | India French Settlements in India | 1962 | Yes | Coup d'état of Yanaon |
| Confederation of Himalayan States |  Bhutan Nagaland Nepal North-East Frontier Agency Sikkim | 1962 | No | In 1962, the Chinese Government proposed a Confederation of Himalayan States.[63][64][65] |
 Federation of the Emirates of the South |  Fadhli Audhali Beihan Dhala Lower Yafa Upper Aulaqi Sheikhdom Alawi Aqrabi Dathina Haushabi Lahej Lower Aulaqi Maflahi Shaib Wahidi | 1962 | Yes | The Federation of the Emirates of the South (Arabic: اتحاد إمارات الجنوب العربي Ittiḥād ʾImārāt al-Janūb al-ʿArabiyy) was an organization of states within the British Aden Protectorate in what would become South Yemen. The Federation of six states was inaugurated in the British Colony of Aden on 11 February 1959, and the Federation and Britain signed a “Treaty of Friendship and Protection,” which detailed plans for British financial and military assistance. It subsequently added nine states and, on 4 April 1962, became known as the Federation of South Arabia. This was joined by the Aden Colony on 18 January 1963. |
| Maphilindo |  Malaya Indonesia Philippines | 1963 | No | Proposals to create a union of the people of the Malay race and deal with the continued decolonisation of Southeast Asia led to leaders of the three countries signing the Manila Accord on 5 August 1963. However, cooperation quickly broke down following the formation of Malaysia by Malaya and other former British colonies in the region, which was opposed by Indonesia and the Philippines.[66] |
 Malaysia | Federation of Malaya Crown Colony of North Borneo Crown Colony of Sarawak Colony of Singapore Also invited:  Brunei | 1963 | Yes | Singapore was expelled from the federation on 9 August 1965, later forming the Republic of Singapore. Brunei Sultan Omar Ali Saifuddien III accepted the idea but rejected after the Brunei revolt. |
 United Republic of Tanzania |  Republic of Tanganyika People's Republic of Zanzibar | 1964 | Yes | |
| Australia | Australia Nauru | 1964–1965 | No | In 1963 the Australian Government proposed that the citizens of Nauru, a United Nations trust territory under Australian administration, would move to Curtis Island and become Australian citizens.[67][68] By that time, Nauru had been extensively mined for phosphate by companies from Australia, Britain and New Zealand damaging the landscape so much that it was thought the island would be uninhabitable by the 1990s. The cost of resettling the Nauruans on Curtis Island was estimated to be £10 million, which included housing and infrastructure and the establishment of pastoral, agricultural, and fishing industries.[69] However, the Nauruan people did not wish to become Australian citizens and wanted to be given sovereignty over Curtis Island to establish themselves as an independent nation, which Australia would not agree to.[70] Nauru rejected the proposal to move to Curtis Island, instead choosing to become an independent nation operating their mines in Nauru.[71] Nauru became self-governing in January 1966, and following a two-year constitutional convention, it became independent in 1968 under founding president Hammer DeRoburt.[72] |
| Territory of the Marianas |  Territory of Guam Commonwealth of the Northern Mariana Islands | 1969 | No | 1958 Saipan integration referendum, 1961 Northern Mariana Islands status referendum, 1963 Northern Mariana Islands integration referendum, 1969 Guamanian unification with the Northern Mariana Islands referendum, 1969 Northern Mariana Islands status referendum |
 United Arab Emirates |  Abu Dhabi Dubai Sharjah Ajman Umm Al Quwain Fujairah Ras Al KhaimahAlso invited:  Bahrain Qatar | 1971–1972 | Yes | Six independent emirates formed the United Arab Emirates on 2 December 1971. Ras Al Khaimah later joined the federation. |
 Federation of Arab Republics |  Libya Egypt SyriaAlso invited:  Iraq Sudan | 1972–1977 | Yes | An attempt by Muammar Gaddafi to build a Pan-Arab state. |
 Arab Islamic Republic | Libya Tunisia | 1974 | No | Proposed by Muammar Gaddafi. |
| Indochinese Federation[73] |  North Vietnam South Vietnam Democratic Kampuchea Laos | 1975 | No | Despite Kampuchea's cooperation with the Vietnamese, the Khmer Rouge leadership feared that the Vietnamese communists were planning to form an Indochinese federation, which would be dominated by Vietnam. In order to pre-empt any attempt by the Vietnamese to dominate them, the Khmer Rouge leadership began, as the Lon Nol government capitulated in 1975, to purge Vietnamese-trained personnel within their own ranks. Then, in May 1975, the newly formed Democratic Kampuchea began attacking Vietnam, beginning with an attack on the Vietnamese island of Phú Quốc.[74][75][76] |
| India | India Sikkim | 1975 | Yes | After independence in 1947, joining the new Indian Union was rejected by popular vote. Sikkim grew closer to India over time, becoming a protectorate and later a suzerainty[citation needed] of India. With Indian pressure and support, Sikkim voted to join India in 1975.[77][78] |
 Republic of Guinea-Cape Verde [79][80] | Guinea-Bissau Cape Verde | 1975 | No | The African Party for the Independence of Guinea and Cape Verde (PAIGC) advocated for the independence of the colonies of Portuguese Guinea and Portuguese Cape Verde, and governed both countries immediately after independence (1974 for Guinea-Bissau, and 1975 for Cape Verde) with the goal of unifying the two. However, following a 1980 coup in Guinea-Bissau, the Cape Verde branch of the party separated to form the African Party for the Independence of Cape Verde (PAICV), ending plans for a union.[81] |
| Indonesia | Indonesia East Timor | 1975–1976 | Yes | Indonesian invasion of East Timor |
 Vietnam | North Vietnam South Vietnam | 1976 | Yes | Fall of Saigon, Reunification Day |
 Solomon Islands | Solomon Islands Republic of the North Solomons | 1976 | No | The Interim Provincial Government announced that they would declare independence on 1 September, ahead of Papua New Guinea's own planned independence day of 16 September. On 1 September, they issued the 'Unilateral Declaration of Independence of the Republic of the North Solomons'. They sought international recognition through the United Nations, but were unsuccessful. They also failed in an attempt to unite with the Solomon Islands. |
| Socialist Union of the Horn of Africa[82] |  Ethiopia Somalia South Yemen | 1977 | No | In early 1977, Castro brought together the leaders of Somalia, Ethiopia and South Yemen to create a socialist federal state in the region. General Mohamed Nur Galal was the former deputy defense minister of Somalia and the vocal point of Somalia's military contacts with Cuba at that time. He was present at the meeting in Aden in March 1977.[83][84] |
 Swaziland | Swaziland KaNgwaneAlso invited:  KwaZulu | 1982–1989 | No | An attempt to transfer the bantustan, along with parts of the Zulu homeland KwaZulu, to the neighbouring country of Swaziland in 1982 was never realized.[85][86] This would have given land-locked Swaziland access to the sea. The deal was negotiated by the governments, but was met by popular opposition in the territory meant to be transferred.[87] The homeland's territory had been claimed by King Sobhuza of Swaziland as part of the Swazi monarchs' traditional realm, and the South African government hoped to use the homeland as a buffer zone against guerrilla infiltration from Mozambique. South Africa responded to the failure of the transfer by temporarily suspending the autonomy of KaNgwane, then restoring it in December 1982 and granting it nominal self-rule in 1984.[88][89] |
  Senegambia Confederation | Senegal The Gambia | 1982-1989 | Yes | A loose confederation was formed, but ended due to the Gambia's lack of interest in integration. |
 Yemen |  North Yemen South Yemen | 1990 | Yes | Yemeni unification |
| Germany | West Germany East Germany | 1990 | Yes | German reunification |
| Union of Soviet Sovereign Republics |  Russian SFSR Byelorussian SSR Ukrainian SSR Azerbaijan SSR Kazakh SSR Kirghiz SSR Tajik SSR Turkmen SSR Uzbek SSR | 1990–1991 | No | 1991 Soviet Union referendum |
 FR Yugoslavia |  SR Serbia Montenegro Bosnia and Herzegovina | 1991 | No | Zulfikarpašić–Karadžić agreement |
| FR Yugoslavia | SR Serbia Montenegro | 1992 | Yes | |
| Balkania | SR Serbia Montenegro Kosova | 1993–2006 | No | Suggested by the Kosovo Albanian politician Adem Demaçi |
 South Africa | South Africa Bophuthatswana Ciskei Transkei Venda | 1994 | Yes | During apartheid the South African Government granted nominal independence to four autonomous bantustans within it. While no external country recognized these states, South Africa strongly promoted their independence and the four mutually recognized each other. As South Africa moved to end apartheid, the African National Congress (ANC) party advocated reintegration of all bantustans, including the nominally independent ones, into a unitary South African state. Resistance to integration by leaders of some bantustans led to violence, s
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