In the years following its independence, the Cuban republic saw significant economic development, but also political corruption and a succession of despotic leaders, culminating in the overthrow of the dictator Fulgencio Batista by the 26th of July Movement, led by Fidel Castro, Che Guevara and Raúl Castro, during the 1953–1959 Cuban Revolution. The new government aligned with the Soviet Union and embraced communism. Massive quantities of advanced Soviet military hardware, including batteries of surface-to-air missiles, flowed to the island, and in October 1962 the Cuban Missile Crisis occurred. Cuba was officially atheist from 1962 until 1992. Following the Warsaw Pact invasion of Czechoslovakia (1968), Fidel Castro publicly declared Cuba's support. Castro's speech marked the start of Cuba's complete absorption into the Eastern Bloc. By the mid-1970s, little would remain of Cuba's political or economic system. During the Cold War, Cuba also supported Soviet policy in Afghanistan, Poland, Angola, Ethiopia, Nicaragua, and El Salvador. The Soviet-Cuban intervention in Angola contributed to the downfall of the apartheid regime in South Africa.