Nkomo remained unchallenged at the head of ZAPU, but the ZANU leadership had become contested between its founding president, the Reverend Ndabaningi Sithole, and Robert Mugabe, a former teacher from Mashonaland who had recently won an internal election in prison. When they were released in December 1974 under the détente terms, Mugabe went to Mozambique to consolidate his leadership of the guerrillas, while Sithole joined Muzorewa's delegation. It had been agreed that the talks would take place within Rhodesia, but the black nationalists refused to meet on ground they perceived as not neutral. The Rhodesians insisted on abiding by the accord and negotiating inside the country. To please both camps the conference was held on a train halfway across the Victoria Falls Bridge on the border between Rhodesia and Zambia; the delegations sat on opposite sides of the frontier. The conference, which took place on 26 August 1975 with Kaunda and Vorster as mediators, failed to produce a settlement; each side accused the other of being unreasonable. Smith afterwards held direct talks with Nkomo and ZAPU in Salisbury, but these also led nowhere; Nkomo proposed an immediate transition to an interim government headed by himself, which Smith rejected. Guerrilla incursions picked up strongly in the first months of 1976.