He became President in 1977, when Bophuthatswana was declared independent by the South African government. On 10 February 1988 he was briefly overthrown by members of a military police unit, led by Rocky Malebane-Metsing of the People's Progressive Party (PPP), who had accused Mangope of corruption and charged that the recent election had been rigged in the government's favour. Mangope was reinstated following intervention by the South African Defence Force. South Africa's government stated that it was responding to a request for assistance from the legal government of a sovereign nation.