>>48510
Uruguay is a successful separatist province, but as a brief conquest it doesn't really count. The Lusophone provinces have tried, sometimes more than once. The earliest anti-colonial conspiracies wanted independence for specific parts of the colony, and long before them, in 1641 Spaniards in São Paulo elected a king among themselves because they didn't want to be subjects of the newly independent Portuguese crown. Pernambuco tried secession twice (1817 and 1824) and got parts of other states on board. Then the empire began to fall apart in the Regency era (1831-1840). Rio Grande do Sul's war of independence was explicitly separatist, others not so much (e.g. rebels in Bahia declared the province a temporary republic until Pedro II reached adulthood) or not at all (liberal and conservative revolts in the imperial core). Even then, balkanization would ensue if one revolt after another couldn't be suppressed. There wasn't any more inherent unity than in the balkanized former Spanish colonies.
In 1892, one political faction in Mato Grosso wanted to declare an independent republic. This was on a state deep inland, only accessibly by sailing to Argentina and up the Paraguay river, without even telegraph communications. It seems they didn't even get to declare independence, though. Later on, in the 1932 civil war separatist intentions were exploited by government propaganda. Some of those fighting for São Paulo did have separatist intentions, but it was a nationwide movement. And as late as 1964, the rebels in Minas Gerais had to assure the public their movement wasn't separatist.