A staunch anticommunist, in 1975 Botha persuaded Vorster and the cabinet to agree to a South African military invasion of Angola in order to prevent the pro-Moscow Popular Movement for the Liberation of Angola (MPLA) from coming to power there. This proved to be an embarrassing failure, for the South African forces had to withdraw. The MPLA took power and then supported the South West African People's Organization (SWAPO) in its guerrilla war against the South African forces occupying Namibia.
Despite this failure, a scandal in the National Party allowed Botha to take over from Vorster as prime minister in September 1978. With Marxist-Leninist regimes in both Angola and Mozambique, Botha saw a communist threat to the whole of southern Africa.
Botha did urge reform of the apartheid system then in place. One of the major reforms that he pushed through was a power-sharing scheme with two minority groups, the mixed-race Coloreds and the Indians. This split the National Party, but part of Botha's constitutional reform was to create a powerful executive state president, and he was the first to fill that post in 1984. While he continued to denounce the exiled and restricted African National Congress (ANC) as a tool of the South African Communist Party (SACP), he allowed some of his officials to begin covert discussions with Nelson Mandela and other key ANC officials from 1985 on. In July 1989 shortly before Botha left office, he met with Mandela, who rejected release on renunciation of violence. Botha lacked the courage to release him unconditionally.
Under Botha's leadership, apartheid then entered its most brutal phase both at home and abroad. Units in the security forces carried out assassinations, torture was rampant, and neighboring states were destabilized. Yet when Botha began to introduce reforms, British Prime Minister Margaret Thatcher was prepared to meet him, and U.S. President Ronald Reagan was well disposed toward South Africa as a former ally in World War II. Reagan's constructive engagement policy let Botha off the hook as far as possible sanctions were concerned until the mass uprising of the mid-1980s, when the United States and other countries did begin to impose sanctions.
Botha did agree to withdraw from Namibia in 1988, under pressure from the United States and in the new context of superpower détente. Botha suffered a minor stroke in January 1989 and left office in August that year. It is unlikely that his fierce anticommunism would ever have permitted him to legalize the South African Communist Party as his successor, F. W. de Klerk, did in February 1990. Unrepentant to the last, Botha died in Wilderness, South Africa, on October 31, 2006.
O'Meara, Dan. Forty Lost Years. Athens: Ohio University Press, 1997.; Pottinger, Brian. The Imperial Presidency: P. W. Botha, the First 10 Years. Johannesburg: Southern Books, 1988.