Poland had fallen and battle was well underway on the Finnish-Soviet front, but, as far as the British and French were concerned, this was the period of ‘phoney war’ or ‘drole de Guerre.’ A huge French army had manned the forts of the Maginot Line throughout winter, but had no plan to attack. But Hitler had a plan. He intended to launch his forces westwards on 17 January 1940, following his so-called ‘Plan Yellow.’ However, the previous week, a German light aircraft had made a forced landing at Malines, in Belgium, and the details the plan were captured by the Belgians and shared with the French and British. On 16 January, Hitler postponed his attack until the spring, not only because Plan Yellow had been compromised but also because his generals felt it was too predictable. They thought a better and less obvious strategy would be to send their main attacking force through the forests of the Ardennes.
If the German plane had not landed at Malines, would Hitler have launched Plan Yellow in January, and would he have been stopped–as the German assault in World War I had been halted at the Marne? Would France not have fallen in June 1940? Perhaps the German generals would have gotten rid of Hitler that summer, as they had been planning, and the war would have come to an end.