In history, we can commonly see that countries broke apart to form their own independent nations. Even in modern times/ post WWII countries still broke apart, like Czechoslovakia and Yugoslavia as some examples. I am wondering if in modern history there has been any TWO nations that diplomatically formed ONE nation. So not something like the EU which is not exactly a unified nation. Thanks!
I am unsure if this counts exactly, but when the former British Somaliland gained independence on June 27, 1960, it became the independent State of Somaliland, and when the Italian-administered former Italian Somaliland gained independence on July 1st, 1960 - 5 days after British Somaliland became an independent country - both merged to form the Somali Republic. It was also expected that French Somaliland (Djibouti) upon independence from France would also merge with the Somali Republic, but vote-rigging by the French during the prolonged French association vs union with Somalia referendum stopped this from happening.