 After use on most of the system, as outlined further, they eventually worked in Botswana after 1959 and reached Mafeking in 1966 when Rhodesia Railways took over operation of the whole system.They replaced the 12th class 4-8-2 locomotives previously used.The 15th class came to dominate the line, to the extent that they became the only type used until the DE2 class diesels were assigned to the Bulawayo–Mafeking trains in 1973.