Leibbrandt represented South Africa at the 1934 Empire Games and won the light heavyweight bronze medal.

Once back in South Africa, Leibbrandt made contact with what he hoped would be pro-Nazi elements among the Afrikaner populace known as the Ossewabrandwag, but its leader Johannes Van Rensburg was found to be unsympathetic to his mission.

[4] Leibbrandt assembled a paramilitary force of less than 60 men from the Ossewabrandwag, recruited during a series of Hitlerite style speeches that he made in the Orange Free State and the Transvaal.

Leibbrandt's group launched a series of small-scale guerrilla warfare operations against infrastructure targets, dynamiting power lines and railway tracks, and cutting telephone and telegraph cables.

During his trial on charges of high treason, Leibbrandt refused to participate except to state that he had acted for "Volk & Fuhrer", and to give a Nazi salute to the court.

To avoid making Leibbrandt a martyr and risk increasing pro-Nazi sympathies among the Afrikaners, the sentence was commuted to life imprisonment by Prime Minister Jan Smuts.

[8][9] Leibbrandt remained politically active in later life, founding the 'Anti-Communist Protection Front' in 1962, and producing a series of pamphlets entitled Wake up South Africa.