There have been and still are plenty of groups who are fighting for independence of their home regions, and many who have been successful, but is there any precedent for groups fighting to leave the country they inhabit solely as to join a neighbouring country, successfully, in the last century or so? I was wondering more specifically about if a situation like this had been achieved through violence rather than democratic means. An ongoing example from recent history might be some of the various groups in Northern Ireland who have attempted to use violence to force the UK government to allow Northern Ireland to unify with the Republic of Ireland. Is there any precedent for a situation like this to occur?

I did some research already and couldn't really find anything, I think because it's quite a specific scenario (One region breaking off solely to unify with a neighbour and excluding more typical independence or autonomy)

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    I thought that the troubles and the subsequent tension were about discrimination. Whether to join Ireland or not was decided in a referendum long before.
    – FluidCode
    May 14 at 15:18
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    IIRC the Troubles began over issues of discrimination but from it formed multiple groups who's final aim was the unification of Ireland, which they then fought for. Pretty sure it was at least one of the IRAs but there's so many I can't recall which they were. May 14 at 16:47
  • Are you only wondering about violence secession? May 15 at 2:03
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    It rather depends on what you mean by secession. Heligoland in 1890 comes to mind: not so much a secession, as a land swap between Britain and Germany. May 16 at 8:56
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    Perhaps the Sudetenland in 1938? As with Crimea in 2014, it's often portrayed as an annexation, but it was very much with the support of the local German-speaking population. May 16 at 9:05

11 Answers 11


The Acre War happened around 1900. Formerly it was a sparsely populated part of Bolivia, beyond the Andes, thus hard to reach from Bolivia. With the rubber boom in the last decades of the XIX c., Brazilians went there to collect rubber and become the majority - It resembles Texas' story but much more remote and sparsely populated.

After various revolts separated by a few years, when control went back and forth between the rebels and Bolivia, at the end Brazil invaded to back the again victorious rebels and got a diplomatic settlement.

  • Some of them wanted independence. But, given the small size and remoteness, it would be much less viable than Texas. It is hard to judge how sincere they were about independence.
  • Brazil had much faster and easier access via the large rivers. To cross the Andes was no easy task.
  • Thus, the promised railway Madeira-Mamoré would really help Bolivia, giving them a pathway to access the Atlantic (via rivers - check in google maps how wide are the Amazon and Madeira rivers before scoffing at riverine shipping)
  • Rubber was the largest business in the region, which explains the interests of the Amazonas State.

The answer appears well liked, so I give two hints more:

  • Amazon states (inclusive Brazil) often worry about land owned de jure but unoccupied de facto. This is one textbook example. It it not just paranoia.

  • if you are interested in amazing diplomacy, study the works of Barão of Rio Branco. He settled various difficult old territorial disputes without firing a shot, and mostly favorably to Brazil. Not just by rhetoric, also by hard work of diplomats digging documents in European archives and understanding how arbitration worked for each specific case. Few faces printed in banknotes really deserve to be there.

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    "resemble Texas' story" might not be universally understood reference May 14 at 19:52
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    @GrzegorzOledzki - Agreed. I've added a link to a standard reference source. Feel free to add in something different Luiz, if you prefer.
    – T.E.D.
    May 15 at 12:53
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    thanks for the fix @T.E.D.
    – Luiz
    May 15 at 18:09

Kashmir might be the biggest example, if you are willing to accept "de facto control" rather than "international recognition". Parts of Kashmir are currently de facto part of Pakistan, with the border being the "Line of Control". Here a region that had been part of India, broke away and joined a neighbour, although international recognition awaits a more comprehensive agreement between India and Pakistan.

Other examples (harvested from Wikipedia's List of border changes) I'm mostly looking at post WW2, as the period before 1945 is too chaotic.

1947 The Dodecanese and Rhodes seceded from Italy and merge with Greece.

May 1961, The Northern part of "British Cameroons" seceded from the colony and became part of Nigeria. "British Cameroons continued for another 6 months before the remainder of the country merged with Cameroon.

Feb 1994 Walvis Bay and the Penguin Islands seceded from South Africa and merge with Namibia There have been other small transfers of territory, between Poland and the USSR, for example. Like Walvis bay, these have generally not involved violence.

Crimea (ongoing) While this is obviously part of an ongoing war, Russian control in Crimea is not being seriously challenged at the moment and so Crimea has de-facto seceded and merged with Russia.

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    Regarding Crimea - AFAIK it was not a "secession" but an "invasion".
    – abukaj
    May 16 at 7:54
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    Crimea didn't secede as such, if you view secession as happening with the consent and cooperation of the inhabitants. Quite the opposite, in fact. Otherwise a good answer.
    – RedSonja
    May 16 at 8:29
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    Kashmir isn't the right example. It declared its independence in order to remain independent, but was soon invaded by Pakistan and then India. The part annexed by Pakistan was annexed without ever asking to the local population whether they wanted to join Pakistan. The part annexed by India went through a formal process, but they had little choice, either they accepted the Indian occupation of they had to prepare for the looming Pakistani invasion.
    – FluidCode
    May 16 at 12:29
  • Re "British Cameroon": There is still an active seccession movement in what they semselves call Ambazonia. While formally a movement for independence, I can tell you from personal discussions with activists that the idea of joining Nigeria is still very much alive.
    – ccprog
    May 16 at 23:59
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    @RedSonja Are you suggesting that people was forced to vote for independence in the 1991, 1992 and 1994 referenda? By who? The crimean authorities? I would need evidence of that.
    – Rekesoft
    May 18 at 15:08

The Greater Poland Uprising (1918-1919) fits your criteria. The Poles in the Greater Poland region fought German rulers to unify with the newly created Second Polish Republic. Although it is a bit of a stretch. Earlier the entire Poland was occupied by Germany/Austria/Russia, and most of it regained independence. It could be argued that the uprising was just the continuation of that process.

  • "Earlier the entire Ireland was occupied by England (later United Kingdom), and most of it regained independence" - fits pretty precisely. May 16 at 8:33
  • @MartinBonnersupportsMonica Yeah it's pretty similar actually. The only difference is the time frame. The Republic of Ireland is already independent for more than century, while Northern Ireland is still under British control. The Second Polish Republic was only one month old when the Greater Poland Uprising began. So the Uprising and the formation of Second Polish Republic were almost simultaneous. Arguably, the Uprising could begin even if the Second Polish Republic didn't exist yet. It began less from a desire to unify with an existing state, but rather to overthrow the occupiers.
    – ciamej
    May 16 at 12:11

There are some good examples following the dissolution of Austria-Hungary;

In 1918, the Kingdom of Croatia-Slavonia proclaimed independence, merged with the newly constituted State of Slovenes, Croats and Serbs and then asked to join Serbia and Montenegro to form the Kingdom of Serbs, Croats and Slovenes.

Similarly, Banat, Bačka and Baranja declared independence and joined the Kingdom of Serbia.

Note that Czechoslovakia was different, Masaryk & comp. operated from (and achieved recognition of Czechoslovakia by the WWI victors) outside of the legal structures of Austria-Hungary.

There are other examples, but less clear cut (if the region was already occupied by the other country's army), e.g. the Republic of Central Lithuania joining Poland, quite a parable to this century Crimea; or if the end result was less than pleasant, e.g. the West Ukrainian People's Republic that joined the Ukrainian People's Republic only to be later overun by the Bolsheviks and included in the Soviet Ukraine.

Not A-H related, but in the same historical period Bessarabia declared independence from Russia and after some time joined Romania.

  • Related to A-H I wonder if we can put here Transylvania, which declared joined Romania in 1918. It is also a successful attempt in the sense that many other examples (Yugoslavia, and Czechoslovakia) fell apart along the previous state lines almost immediately after the Iron Courtain were raised.
    – Greg
    May 17 at 5:21

Not an example of a "violent" secession, but I think this perfectly captures the title question.

Hatay Province of modern Turkey seceded from Syria and on 29 June 1939, following a referendum became a Turkish province.


There are a lot of qualifications to your question that make a lot of the answers slightly miss the premises. I would argue that there is a systematic reason for the discrepance. If a group of secessionists wants to leave one country to join another, this by definition adds a third party to the conflict. It can never be a fight between the country holding the territory and the people wanting to leave, but must always include a positioning of the country they want to join. In fact, most of the time the "receiving" country will take an active part. And the military might of the two countries involved will be much more of a deciding factor than the secessionist fighters themselves could hope to be.

In that sense, here is another example that does not quite fit:

In 1918, both Azerbaijan and Armenia declared independence from the Russian Empire. Both countries claimed the Nagorno-Karabakh region for themselves. In August 1919 both countries signed a "provisonal treaty" that accepted Aseri sovereignity of the region under the rules of a partial autonomy. After several more rounds of conflict, in 1923 Nagorno-Karabakh was finally declared an Autonomous Oblast of the Azerbaijan Soviet Socialist Republic.

After 1985, the Armenians living in the region started to rebel again against the Azerbaijan rule. Until the end of the Soviet Union, this remained a more or less small scale uprising, but in 1992 escalated to a war between the two countries.

In 1989 the Armenian Supreme Soviet had declared Nagorno-Karabakh to be a part of Armenia. In 1991 Nagorno-Karabakh declared itself independent. In the years of war 1992-94, it were the Azerbaijan and Armenian armies, with the help of mercenaries on both sides, that actually fought. Since the truce of 1994 the Republic of Artsakh maintains it is an independent country, despite its ability to rule being always dependent on the presence of Armenian forces and assistance from the Armenian government. Since the 2020 war, when Artsakh lost one third of its territory, Russian peacekeeping forces (yes, in this case I think they can be called such) are another part of the equation.

So, was there ever a true movement of the people to join Armenia, or was it the Armenian government hiding their annexation intent behind so-called freedom fighters? Was the Nagorno-Karabakh independence ever a real aim, or only a disguise? Was it, in any sense of the word, ever part of Armenia? The answers obviously depend on which side you ask.

  • +1, but I guess (in a honest moment) all sides would agree that independence was/is not Karabakh's end goal?
    – Jan
    May 17 at 8:48

The most recent event of such kind is Autonomous Republic of Crimea, which seceded from Ukraine in 2014 and then voted to join Russian Federation in 2014 Crimean status referendum.

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    To the voters: when voting on answers please only take into account whether it answers the question or not, and not whether you like or dislike the event which the answer is referring to.
    – vsz
    May 15 at 19:16
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    The issue isn't whether people like or dislike the event, but that calling Crimea a secession followed by unifying with a neighboring country is dishonest at best. Russian troops invaded Crimea and overthrew the government. The dissolution of their government was voted on by representatives under duress, and their constitution was violated as a new prime minister was appointed without consultation of the President of Ukraine, as the office was vacant due to Yanukovych being removed from office on February 22nd. It was a nearly bloodless annexation, not secession. May 16 at 1:44
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    I think the jury is out on whether that one is meets the question's criterial of "successful" as it is still contended as an illegal annexation in an active shooting war zone.
    – simbo1905
    May 16 at 10:58
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    @DavidJacobsen calling it purely an invasion without any context is also sort of dishonest. In 2014 the main government was violently overthrown, and the eastern regions of the country stayed loyal to the old government, this is where the entire conflict started and why they wanted to secede. Yes, Russia very likely did provide support for the separatists, but if you look at the 2019 election results and notice that the pro-Russia party won all Donbas districts even in parts under Ukrainian control, you can see that the separatists didn't vote for separation merely due to duress.
    – vsz
    May 16 at 15:44
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    @simbo1905 : between 2014 and 2021 there was no active war zone, and as other answers already mentioned, Crimea is not seriously challenged even now. And even if it was, just being in a war zone doesn't mean one cannot call it secession. The US civil war was also a secession, even if it was ultimately defeated. And Kosovo is also considered to have been seceded, even if Serbia and many other countries still regard it as illegal.
    – vsz
    May 16 at 15:47

Vietnam possibly.

is there any precedent for groups fighting to leave the country they inhabit solely as to join a neighbouring country, successfully, in the last century or so?

A movement was formed which rebelled against a colonial power (France) and succeeded by a combination of violence and political activity. This resulted in the formation of North Vietnam and South Vietnam. The south reneged on an agreement that formed part of the settlement and this led directly to the war which the US became mired in. This involved both an invasion from North Vietnamese forces and Southern Vietnamese rebels.

This ended with the reunification of Vietnam.

So you have a partition of a country, a civil war and invasion and finally a reunification. In this case the Southern rebels fought to join the neighboring North Vietnam (and did). Seems to match your requirements.


The Saarland a part of France after the 2nd world war and voted to join Germany in 1955. It became a federal state of Germany in 1957.

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    Please provide more details to explain how this fits the bill. Or how it is 'correct' to describe it in this way: The Saar seems to have been a 'protectorate' under special occupation by France. And France wished to annex it fully. But did not? May 16 at 21:38

The German Reunification might fall under your constraints.

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    You should include some detail of what happened and how you see that fitting the question (bearing in mind that even Wikipedia links can rot).
    – Steve Bird
    May 16 at 12:22
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    Please explain from what/whom the GDR seceded, in your view. The Warsaw Pact was not "a country" of which the GDR was a part? May 16 at 21:36

Hong Kong was, for nearly 100 years, a British Territory administered by the British government, originally during the Opium wars, when China was still under the rule of the Manchurian Qing dynasty, multiple regime changes ahead of the current People's Republic of China.

In 1997, the formal lease for the region expired, and a negotiated reunification with the people's republic of china was negotiated, and while there was no explicit threat of violence or anything, it was done with quite a lot of apprehension by the citizens of the city, and with the geopolitical backdrop of "if the Chinese wanted to take it, there wasn't much the British could realistically do about it, and the expiration of the lease pretty much had international law in China's favor". For the last 20 odd years, the territory has been ruled under the "One country, two systems" uneasy truce, and had done so relatively stably.

Obviously, the recent political crsis has made it unclear how stably and smoothly reintegration of Hong Kong into China has gone, but I know of no observers who expect anything like Hong Kong independence or a return of the region to the United Kingdom to even be an imaginable prospect.

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    This example does not meet the criteria stated in the question. May 16 at 16:18

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