[1] After working in the gold mines of South Africa, he fled to neighboring Bechuanaland (now Botswana) and set off for Tanganyika (now Tanzania).
Mnyika and fellow SWAPO activist Maxton Joseph Mutongolume were arrested in Southern Rhodesia (Zimbabwe) and deported to South Africa, where they were charged with leaving the country illegally.
He was one of the founding members of the South West African Liberation Army (SWALA), which eventually transformed into SWAPO's armed wing of PLAN.
In 1966, Mnyika was captured during the Battle at Omugulugwombashe, the first military conflict of the Namibian War of Independence against South Africa.
In February 1968, he was convicted on terrorism-related charges by the occupying apartheid officials from South Africa and sentenced to life imprisonment.