'Noah' (iii) was a British and Canadian contingency plan for a withdrawal from the line of the Maas river in the German-occupied Netherlands in the event that the Germans flooded the area (2/7 December 1944).
If flooding did occur, Lieutenant General G. G. Simonds’s Canadian II Corps of General H. D. G. Crerar’s Canadian 1st Army was to evacuate the area, treating the operation as a normal withdrawal in the face of opposition. Careful consideration was given to the problems of coping with traffic control, civilian refugees and livestock.
On the evening of 1 December Crerar sent a senior staff officer to warn the II Corps headquarters, where Major General T. G. Rennie of the British 51st Division was temporarily in command during the absence of Simonds, of the importance of being ready for flooding by the Germans, who in fact started the process on the following day as Major General G. H. A. MacMillan’s British 49th Division reported that the dykes had been blown to the north of Elst and to the west of Arnhem.
The 'Noah' (iii) plan was then put into practice and an orderly evacuation began. The flood spread west in the direction of Zetten and Heteren until, after three days, it reached an approximate equilibrium with the northern three-quarters of the former 'island', to the west of the line between Arnhem and Nijmegen and extending to the west past Octen, under water. In conjunction with the flooding, the Germans launched a local attack against the 49th Division on 4 December. This attack was sharply repulsed, and the situation gradually settled, units of both the 49th and 51st Divisions retaining footholds on the 'island', under the headquarters of the former from the morning of 6 December with the Nijmegen bridge still well covered. Both divisions' headquarters had moved to positions to the south of the Waal river by 12.00 on 7 December.