but was also used as a pretext to prosecute hundreds of activists, among them most of the ANC's leadership, in the Treason Trial. Before the trial was concluded, the Sharpeville massacre occurred on 21 March 1960. In the aftermath, the ANC was banned by the South African government. It was not unbanned until February 1990, almost three decades later. Exile in Lusaka After its banning in April 1960, the ANC was driven underground, a process hastened by a barrage of government banning orders, by an escalation of state repression, and by the imprisonment of senior ANC leaders pursuant to the Rivonia trial and Little Rivonia trial. From around 1963, the ANC effectively abandoned much of even its underground presence inside South Africa and operated almost entirely from its external mission, with headquarters first in Morogoro, Tanzania, and later in Lusaka, Zambia. For the entirety of its time in exile, the ANC was led by Tambo – first de facto, with president Albert Luthuli under house arrest in Zululand; then in an acting capacity, after Luthuli's death in 1967; and, finally, officially, after a leadership vote in 1985. Also notable about this period was the extremely close relationship between the ANC and the reconstituted South African Communist Party (SACP), which was also in exile. uMkhonto we Sizwe In 1961, partly in response to the Sharpeville massacre, leaders of the SACP and the ANC formed a military body, Umkhonto we Sizwe (MK, Spear of the Nation), as a vehicle for armed struggle against the apartheid state. Initially, MK was not an official ANC body, nor had it been directly established by the ANC National Executive: it was considered an autonomous organisation, until such time as the ANC formally recognised it as its armed wing in October 1962. In the first half of the 1960s, MK was preoccupied with a campaign of sabotage attacks, especially bombings of unoccupied government installations. As the ANC reduced its presence inside South Africa, however, MK cadres were increasingly confined to training camps in Tanzania and neighbouring countries – with such exceptions as the Wankie Campaign, a momentous military failure. In 1969, Tambo was compelled to call the landmark Morogoro Conference to address the grievances of the rank-and-file, articulated by Chris Hani in a memorandum which depicted MK's leadership as corrupt and complacent. Although MK's malaise persisted into the 1970s, conditions for armed struggle soon improved considerably, especially