JOHANNESBURG — Edgar Z. Tekere, who was imprisoned for a decade with Robert Mugabe during the struggle to end white minority rule in Rhodesia, and later unsuccessfully challenged Mr. Mugabe’s political domination of what had become an independent Zimbabwe, died on June 7 in the eastern city of Mutare, Zimbabwe. He was 74.

The cause was prostate cancer, a family friend, Ibbo Mandaza, said.

In a memoir published in 2007, Mr. Tekere largely blamed Mr. Mugabe for building a nation whose people “live mostly in fear of their own government, of a state machinery, born out of the forces of liberation, but now, regrettably, more associated with ruthlessness and naked force.”

Mr. Tekere said he accepted his “share of responsibility” for the failure of his generation to establish institutions that would have safeguarded democracy....