'Nan' was a US deception created and implemented as a supplement to the 'Rosebud' undertaking to help validate, in German minds, the existence of Lieutenant General George S. Patton’s US 1^st Army Group in south-eastern England in a position to launch the Allied forces 'real' invasion of France in the Pas de Calais area after the launch of the 'diversion' of the 'Neptune' (iii) landing in Normandy (July 1944).

'Nan' was a simulation of a two-day command post exercise by the fictional US 17^th Division in the area of Studland Bay and Wareham.