'Siesta' was a British unrealised and Canadian offensive against the German forces holding the Nijmegen salient to the south of Arnhem in the German-occupied Netherlands along the Betuwe river (November 1944).

Early in November 1944, when General H. D. G. Crerar’s Canadian 1^st Army assumed responsibility for the Nijmegen salient, Field Marshal Sir Bernard Montgomery, commanding the Anglo-Canadian 21^st Army Group, instructed the Crerar to plan offensive operations 'northwards across the Nederrijn, to secure the high ground between Arnhem and Apeldoorn with a bridgehead over the IJssel river', and consideration was then given to 'Siesta' as a preliminary operation to clear the 'island' between the Waal and Nederrijn rivers as far east as the Pannerdensch Canal. The concept was still under active consideration by Montgomery and Crerar at the end of November, but the planning for this undertaking, which Montgomery described as 'important', was complicated by the current regrouping of formations within the 21^st Army Group. Later, when the Germans flooded the 'island' as a defensive measure, it became clear that the operation could not be considered, at least in the immediate term.