On 19 April 1960 SWAPO was founded as the successor of the Ovamboland People's Organization that was established in 1959. During 1962 SWAPO had emerged as the dominant nationalist organisation for the Namibian people, co-opting other groups such as the South West Africa National Union (SWANU), and in 1976 the Namibia African People's Democratic Organisation. SWAPO used guerrilla tactics to fight the South African military. On 26 August 1966 the first major clash of the conflict took place, when a unit of the South African Police, supported by South African Air Force, exchanged fire with SWAPO forces at Omugulugwombashe. This date is generally regarded as the start of what became known in South Africa as the Border War.