'Nimbus' was an Allied one of many training exercises in the period leading toward 'Neptune' (iii) and 'Overlord' (September 1943).

Following 'Euclid', in which no troops were landed, 'Nimbus' involved one infantry battalion and a field battery of Major General E. H. Barker’s British 49^th Division of Lieutenant General J. T. Crocker’s British I Corps. The two units were landed under the cover of 'attacks' by light bombers and fighter-bombers.

On 6 September Crocker held a discussion which foreshadowed many of the techniques that were to be used in the Normandy on D-Day: these included the arrangement by which the DD amphibious tanks were used as the first wave of the assault, followed some minutes later by the AVREs (Assault Vehicles Royal Engineer), with the leading infantry a short distance behind them. The concept assumed that fire support before the landing would be afforded by self-propelled artillery, rocket craft and heavy bombardment by the supporting warships.