Government started within another government

Question

Has an independent constitution ever been enacted and claimed the territory of another independent constitution in whole or part, and did its government actually exist after enactment within the claimed territory?

The only incomplete examples I can find are for a time, it was popular for Somali sub-qabil diaspora to enact constitutions but never actually perform government functions not even armed rebellion.

Also, I can find rebellions, but the constitutions seem to come later if at all.

Has an independent constitution ever been enacted and its government manifested a presence after such enactment within another independent constitution's territory regardless of where the rebellious constitution was actually physically "signed"?

Answer 1

There are too many examples of this kind.

• Secession of the USA from Great Britain

• American civil war

• Civil war in Russia in 1918-1922, particularly, secessions of Ukraine, Georgia and other territories.

• Dessolution of the USSR, particularly secessions of the Baltic republics, as well as Russian SFSR itself.

• Secession of Chechen republic from Russia.

• Secession of Kosovo from Yugoslavia

• Secessions of South Ossetia and Abkhazia from Georgia

• Secession of Transdnistria from Moldova

• Pretty much every anti-colonial war

• Taiwan vs. China

and so on and so on.

Answer 2

In 1984, an Austrian artist declared the Republic of Kugelmugel (about 8 m in diameter and situated right in the Austrian capital Vienna). He pulled a stunt by printing and publishing his own stamps and ran into expected and some unexpected troubles with various authorities accordingly. His republic was doomed as a sovereign entity among nations, but he ultimately received personal protection from being fined as he was seen as a likeable outsider (and perhaps of interest to the tourists also).