Johannes Willem (Jan) Viljoen was born in 14 May 1812, Winterhoek. Having moved from Oudtshoorn to the present Orange Free State in 1843, he settled near Winburg, where he joined the Voortrekker group of the population, hostile to H. D.Warden. Together with five others from among the Voortrekker element in Transorangia, he was imprisoned at Colesberg in 1846 for anti-British activities. Released after a few months, he took part in the Battle of Boomplaats and because of this had to flee across the Vaal River. He settled near present-day Zeerust and called his farm Ver Genoeg. His wife was Maria Catherina Messer, daughter of the German missionary J. G. Messer (in the service of the L.M.S.). Together, they had fifteen children.
Viljoen undertook very many hunting trips to the interior, including one with Petrus Jacobus (Piet) Jacobs, W. Prinsloo and other Boers as far as Lake Ngami in 1851 and the next year accompanied James Chapman to the Kalahari. On this trip it was only Viljoen's friendship with the chief Sekomi (also written as Sekgoma) that saved him from death after the Transvaal Boers had in the mean time become engaged in a war with the Bechuana tribes. Sekomi allowed Viljoen to escape, although he knew that Viljoen, as field-comet would have to take up arms against the Bechuanas. When he regained the Transvaal, Viljoen had in fact to take part in the war against Sechele (called Segeel by the Boers), the ally and kinsman of Sekomi. Viljoen acquired the nick- name of' Jan Segeel' - due, it is said, to his outstanding bravery in the campaign. In 1854 he hunted on the border of Matabeleland. In 1857 he and other Boer hunters penetrated as far as the Shashi River and two years later, again in the company of Piet Jacobs, he penetrated even farther north into the region west of the Gwaai River, to where the western border of Rhodesia extends today. During the following five years he often returned to this region and to Western Matabeleland.
Viljoen was the eyes and ears of the Pretoria government on the entire western front. He maintained very friendly relations with various chiefs, was a fervent supporter of the Hervonnde Kerk and was actively hostile to other Dutch Churches in the Western Transvaal. In the political disturbances which led to civil war in the Transvaal in 1863 Viljoen played a leading part.
With his 'volksleger' (people's army) Viljoen, as 'commandant-general', opposed Paul Kruger's 'staatsleger' (government forces). After a short skirmish Kruger defeated him between Pretoria and Rustenburg in Jan. 1864. The following year Viljoen, Jacobs and three other hunters were the first Boers to be allowed by Mzilikazi to hunt in Mashonaland. Viljoen was also on friendly terms with Henry Hartley, Rhodesian hunter and discoverer of gold. Throughout the seventies Viljoen continued to hunt north of the Kalahari, in Mashonaland and in other parts of what is now Rhodesia, penetrating to regions where no other Whites, as far as is known, had ever been. After that he lived quietly on his farm, but in the First Anglo-Boer War he led a commando against Montshiwa, who, while the major part of the Republican forces was occupied elsewhere, was creating trouble on the western border. Some authorities consider that, of all the hunters he came closest to Piet Jacobs's unofficial record of 500 bull elephants. His descendants still assert that Viljoen saw the Victoria Falls before Livingstone. He died on 30 April 1893 on his farm Ver Genoeg (Marico).