The French sought to assure the British that they would act to prevent the using bases in the Netherlands and the Meuse valley and to encourage the Belgian and Dutch governments. The politico-strategic aspects of the plan ossified French thinking, the Phoney War led to demands for Allied offensives in Scandinavia or the Balkans and the plan to start a war with the USSR. French generals thought that changes to the Dyle-Breda variant might lead to forces being taken from the Western Front. French and British intelligence sources were better than the German equivalents, which suffered from too many competing agencies; intelligence analysis was not as well integrated into Allied planning or decision-making. Information was delivered to operations officers but there was no mechanism like the German practice of allowing intelligence officers to comment on planning assumptions about opponents and allies. The insularity of the French and British intelligence agencies meant that had they been asked if Germany would continue with a plan to attack across the Belgian plain after the Mechelen Incident, they would not have been able to point out how risky the Dyle-Breda variant was. May wrote that the wartime performance of the Allied intelligence services was abysmal. Daily and weekly evaluations had no analysis of fanciful predictions about German intentions and a May 1940 report from Switzerland, that the Germans would attack through the Ardennes, was marked as a German spoof. More items were obtained about invasions of Switzerland or the Balkans, while German behaviour consistent with an Ardennes attack, such as the dumping of supplies and communications equipment on the Luxembourg border or the concentration of "Luftwaffe" air reconnaissance around Sedan and Charleville-Mézières, was overlooked. According to May, French and British rulers were at fault for tolerating poor performance by the intelligence agencies; that the Germans could achieve surprise in May 1940, showed that even with Hitler, the process of executive judgement in Germany had worked better than in France and Britain. May referred to Marc Bloch in "Strange Defeat" (1940), that the German victory was a "triumph of intellect", which depended on Hitler's "methodical opportunism". May further asserted that, despite Allied mistakes, the Germans could not have succeeded but for outrageous good luck. German commanders wrote during the campaign and after, that often only a small difference had separated success from failure. Prioux thought that a counter-offensive could still have worked up to 19 May but by then, roads were crowded with Belgian refugees when they were needed for redeployment and the French transport units, which performed well in the advance into Belgium, failed for lack of plans to move them back.