The first Boer Republic was established in 1795 out of the district of Graaff-Reinet followed a few months later when the district of Swellendam declared itself a republic. Both republics were later conquered after the British took control of the Cape from the Dutch power. A lot of folks often have no awareness of this important fact often erroneously presuming that the first Boer Republics arose during The Great Trek. This fact is important because it is a stark example demonstrating that the Boers have had a long running desire for independence in Africa while the Cape Dutch did not. I have mentioned these first Boer Republics before, but recently found a map outlining the areas where they were as someone made a map of the Graaff-Reinet & Swellendam districts during the era of Dutch / VOC rule up to 1795. Theses districts were on the Cape frontier where the Boers emerged [ from the Trekboers ] starting just a few decades after the initial arrival of the VOC at the Cape & where the Boer people lived until the Great Trek of the early to mid 19th cent took them across the Orange [ Gariep ] River & then the Vaal River.      

The red / white & blue horizontal tri color flag was used for both republics of the Cape frontier.
 
                                                            

For further reading: The First Boer Republic.