'ECM' was the designation of Allied military convoys (together with a numerical and sometimes a letter suffix) carrying motor transport from Falmouth to the Seine Bay area of northern France within the context of 'Overlord' and subsequent land operations (June/July 1944).

The first of these convoys was ECM.1 of 8/9 June 1944 with 15 US 'Liberty' ships, and the last of the 31 convoys was ECM.27 of 10/11 July with 23 US 'Liberty' ships.