'CM' was the designation of Allied military convoys (together with a numerical and sometimes a literal suffix) plying from Cape Town or Durban, South Africa, via Kilindini, Kenya, to the Red Sea ports but especially Aden, and as such reciprocals of the 'MC' series (March 1940/April 1945).

No data appear to have survived for the initial CM.1 convoy of this 'Cape Military' series, while CM.2 of 14/24 July from Cape Town to Mombasa included the 16,738-ton British Ranchi as its armed merchant cruiser escort. The last of the series was CM.61A of 25 March/1 April 1945 from Durban to Kilindini with the 8,331-ton British City of Canterbury escorted by the corvette Jasmine.

There was also a single 'CMA' convoy from Durban to Mombasa on 22 June/1 July 1940 with six merchant vessels escorted by the heavy cruiser Kent.