 The original (February) plan for Operation Anger had called for an immediate crossing of the Nederrijn near Oosterbeek as soon as the river was reached, if the situation allowed it (Operation Quick Anger). Alternatively, if the German defenses were considered too strong, a better prepared crossing downstream at Renkum could be made (Operation Anger). However, Crerar had ruled that operations could not be made against Arnhem until II Corps had crossed the IJssel and advanced on Apeldoorn, and so Anger could not yet proceed. Additionally reconnaissance patrols on 3 and 4 April determined that German observation posts and positions on the Westerbouwing Heights overlooking the river would make crossing the Nederrijn dangerous. Attempts were made to create smokescreens obscuring the southern bank of the Nederrijn from the watching Germans, a technique that had proved successful in the buildup to Operation Plunder. The screen stretched from the town of Randwijk, 16 kilometres (10 miles) west of Arnhem, along the south bank of the river to Huissen, south of Arnhem, but strong winds and a lack of appropriate generators reduced its effectiveness. Additionally the ground on the Island was deteriorating and on 7 April, after considering various alternatives, Foulkes decided Arnhem must be attacked from the east, across the IJssel.
