He joined the African National Congress (ANC) in 1956 and served eight years' imprisonment on Robben Island, from 1964 to 1972, for his work with Umkhonto we Sizwe.
[1] The ANC was banned in 1960 by the apartheid government, but Diale covertly joined the party's new armed wing, Umkhonto we Sizwe (MK), and underwent military training.
In January 1964, his unit was arrested; after being severely tortured, they were convicted of sabotage and imprisoned on Robben Island.
[1][2] After his release, Diale was subject to a banning order which, for the next four years, restricted his movements and political activities.
In April 2011, President Jacob Zuma awarded Diale the Order of Luthuli in Silver for "his excellent contribution to the struggle against apartheid and for his selfless sacrifices for the attainment of freedom for all in South Africa".