Which event foiled the guerilla plans of the MK in 1963?

The Rivonia raids in 1963 were a critical turning point for the African National Congress's armed wing, Umkhonto we Sizwe (MK), as they significantly disrupted their guerrilla operations. During these raids, police captured key leaders of the MK, including Nelson Mandela, who was later sentenced to life imprisonment. This not only dismantled the leadership structure of the MK but also severely limited their capacity to coordinate attacks and carry out their planned guerrilla warfare strategies against the apartheid regime.

The other events mentioned are notable in South African history but did not directly thwart the operations of the MK in the same way the Rivonia raids did. The Battle of Blood River, for instance, occurred over a century before and is associated with conflicts between the Voortrekkers and the Zulu Kingdom. The Sharpeville Massacre, while pivotal in galvanizing international opposition to apartheid, preceded the formation of MK and was more about civil rights protests than military operations. The Soweto Uprising, occurring in 1976, was a student-led protest against educational policies and did not directly impact the military activities of MK in 1963. Therefore, the Rivonia raids are accurately identified as the events that foiled the guerrilla plans of the MK